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    Silver Member Seismic's Avatar
    Generation
    4th Gen
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    Custom
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    Jun 2004
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    Queensland
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    Cool 4th Gen JDM Digital Climate Control Conversion

    It was the summer of 2006/2007 that I did this coveted conversion and I have been holding onto my writeup ever since. With recent mentions of the conversion I thought it might be time to dig through my old hard drives and find it. So, here it is folks - enjoy:

    I remember distinctly my first PA meet. My baby was shmick – an evening’s worth ofsponging, scrubbing, buffing and shining had been well worth it. I felt like my car would be the one turning everyone’s heads.

    But … it was bone stock – an S model at that! And unbeknownst to me was the fact that nearly everyone else who attended the meet had spent the previous evening in a similar fashion with similar results. Still proud of my car I began to wander around, inspecting everyone else’s JDM bits: foglights, half-mast antennae, parking assist poles, interior re-trims, upgrade wheels, suspension, brakes etc etc.

    By the time I met AdReNaLiN I was starting to think, “Man, I’ve gotta get me some mods – NOW!”. Kind of reminds me of the scene in FNF where Brian says, “I Need NAWS!” So then, AdReNaLiN starts talking about a digital climate control mod. Desperate to start chalking up my list of done things I nod rapidly and say, “tell me more …”

    Up until a few weeks ago there was nearly 3 years worth ofdust on top of a box in my garage. It should be obvious where I’m heading with this so you’ll know what was in the box. That’s right – the coveted JDM Climate Control! “Why so coveted?” I have had to ask myself time and again over the past 3 years. Well, with the benefit of hindsight I have to answer that this is not an easy project. It is not for the squeamish nor the soldering-iron-a-phobic. In all honesty it was one of the most gruelling experiences I’ve had with my car. I would think that the deterrent effect that the difficulty of this conversion has on people has something to do with the very low number of successfully completed conversions that are out there. Finding all the right parts, or difficulty thereof would also be a contributing factor.

    I know several people who, like me, have had a similar box sitting in their garage for varying lengths of time, just waiting for the appropriate window of opportunity. In fact, I only know of 1 other successful conversion in Australia (at the time of original writing) and this was achieved with the assistance of a genuine JDM wiring loom (Mark knows who he is!) Correct me if I’m wrong, there may be others out there in this great country of ours who have braved the frontier of digitally controlled blowing air.

    Before I start getting into the nitty-gritty, I need to give lots of credit to a certain Jean Rene Cormier. If the topic of my write-up caught your eye and a deep-seated excitement began to rise in your spirit – you will most likely have already stumbled across this site:

    http://www.jrcormier.com/prelude/jdmclimatecontrol.php

    There may be others who tackled this project prior to JRC,but JRC is widely regarded as the pioneering publisher of the authoritative conversion guide. My aim here is not to duplicate the JRC writeup but make it specific for the Aussie lude, add a few of my thoughts and experiences along the way, and provide plenty of photos to clarify a few details. I should also state that I have been in contact with Jean Rene, who has granted his permission to reference his site in this writeup – thanks JRC!

    What is Digital Climate Control?

    The Japanese Domestic Market Preludes were available with digital climate control (DCC) in place of the manual climate control units that we have in the AusDM model. It is said time and time again that the Japanese always keep the best for themselves – this is a perfect example.



    The most noticeable difference is the control unit itself, a sleek smoked glass control panel with fewer switches replaces the push-button, temperature slider, fan-speed slider unit we all know and love. In fact, the DCC unit only has one switch and that is for the rear-window demister. All the other controls are soft-touch buttons: Recirculation mode, windscreen defrost, manual a/c on/off, manual fan-speed select, manual vent mode select, temperature up/down, full auto mode, and off. Depending on whether you are letting the unit control the vents and fan speed, or setting these yourself the display will either show you the set temperature only or a mixture of temperature, current vent selection and fan speed – beautiful to look at! Especially when you’re used to the old one!



    Six sensors feed information to the control unit, allowing it to determine the current cabin temperature, heater core temperature, air temperature inside the air conditioning evaporator, and how the external temperature, vehicle speed and level of direct sunlight affect these temperatures. Based on all this information, the unit can make adjustments to the air-conditioning, heating system water valve, mixture of cabin air and heated air, fan speed, and vent settings to achieve the desired temperature setting.

    What parts do I need?



    In order to get the DCC system working properly, you will need the following components (click on the links for pictures):
    Optionally, you can also use the water valve and solenoid that is fitted to the JDM Preludes with DCC. This replaces the water valve in the AusDM with the cable through the firewall. The solenoid receives an activate/deactivate signal from the control unit and opens or closes the water valve respectively. Your existing cable operated water valve will work fine though. Your old temperature slider is actually connected to a mechanism that not only controls the air mix (how much air comes directly from the blower motor via the evaporator versus being diverted through the heat exchange fins in the heater core), but the position of the water valve also. The cable going through the firewall to operate this valve piggy-backs off of this mechanism.
    Additionally, I would recommend some replacement heater hoses when you’re looking for the parts. There are two hoses that connect to the copper pipes of the heater unit coming through the firewall. One is a short one that bends around and attaches to the water valve – the second is alonger one that connects to the engine head underneath the intake plenum on the passenger side of the engine bay. These hoses fit on quite tightly, and after years of use you will probably have to cut them off with a Stanley knife. If you are able to get them off without cutting them, they may be too damaged to reuse – better safe than sorry!

    The part numbers are:

    79721550000 - This is the short hose that goes to the valve, $17.75
    79725550010 - This is the longer hose to the engine head, $45.97

    Any Honda parts department will stock these (or be able to overnight them from the warehouse) and it cost me $64.00 for the two of them.

    There is a third hose running from the other side of the water valve to the head just underneath the distributor which it might not be a bad idea to replace while you’re here. I don’t know the part number (but the Honda parts folks will be able to add it to the set) but it is about $50 from memory.

    Finally, before you embark on this wild adventure bear this in mind: to install some of the parts you will need to remove the evaporator unit. This is part of the air conditioning system and so therefore you’re a/c will need to be degassed. If you have the older R12a gas (1992-1993 models) you will probably have to convert the system to R134a before you can use the a/c again. This will likely set you back around $300 as opposed to about $100 for a normal R134a regas, so factor that into your budget!

    Where do I get these parts?

    As I mentioned above, get the hoses brand new from Honda parts. You’ll have a warranty and the assurance that the parts are new and will fit properly.

    eBay seems to be the best place to find just about anything these days, so lookthere for the JDM stuff. There is usually a DCC on there, but make sure you try to get all the sensors and airmix motor too. The main controller is the easiest to come across but this will NOT work on its own.

    JRC has some ideas as to where to source the other parts if you’re stuck, but ask around the forums. There are those here on PA that seem to have all things JDM like Skinnyboy who can probably source things for you.

    Otherwise, if you have access to a JDM front cut you are in conversion heaven! Not only will you have ALL the parts you need at your disposal, but you will also be able to see how it all should look before you pull it out. And … if you have to pull it out of the cut, you’ll have had practise before trying to put it back into your car!

    I originally purchased the control unit with two of the sensors for $20. I was lucky enough to find all of the sensors and the air mix motor separately for $100. But you can expect to pay anywhere between $150 and $450 for all this stuff depending on where you get it from and how much freight you have to pay etc.

    What tools will I need?


    If you’re confident enough to give this a shot, you should already have all the tools you need:
    • Screwdrivers (flat blade and Phillips head)
    • Socket wrench (metric sizes 10, 12 and 14, extender and a 12mm deep socket)
    • Pliers (multigrips will come in handy and some long nosed)
    • Shifting spanner
    • Wire cutters
    • Stanley knife
    • Soldering iron
    • Heat shrink tubing
    • Black electrical tape
    • Cable ties
    • Plenty of hookup wire
    • Plastic gear grease
    • Car ramps or stands and a jack
    • Oil/coolant drain tray
    • Working light
    • Rags and some good soap and a scrubbing brush
    If you have a workshop manual, or access to online Honda manuals, you may wish to study these carefully and have access to them during the project. I was not so lucky, and I hope this writeup will be comprehensive enough that most will not need them.
    With the wire, there are basically two sizes (or gauges) of wire used in the harness. Most of the wires are just for signal or low current connections and a couple are larger for high power connections – these are mainly for the blower motor. Whether you have some spare wire lying around or you need to go to Jaycar or something to get some, look for wire that is about the same size as the two sizes you’ll find in the wiring harness but still flexible. It would be a good idea to get a few metres of several different colours so that you don’t get too confused when you start hacking into the car’s colour-coded wiring.

    What else should I be aware of before I start?

    People’s experience and confidence when working on their cars will vary, so give yourself an appropriate amount of time to do this. You can complete the project in stages if time is a factor – I did. The first stage is to replace the control unit and hookup most of the wiring so that you can still control the fan and vents manually, you just won’t have a/c. This can be done over a weekend.

    The second stage is to basically do all the rest – this involves having you’re a/c degassed, draining your coolant, removing the heater hoses, and pulling your dash, evaporator and heater unit out which basically leaves the car un-drivable. You’d be wise to allow at least a solid four days for that if you have no other vehicle to get around in.

    Due to other circumstances (search for my numerous posts about how to repair dry joints on the manual climate control unit), I have only had air conditioning working in my car for 1 summer out of the last 3. So I have become used to 3-60 air conditioning (2 windows and a sunroof open at 60 km/hr) but if you currently have operating air conditioning, consider tackling this project in winter especially if you’re going to take it one step at a time.

    If you are contemplating an engine conversion, this may alsobe a good time to try this out since your car won’t be on the road for a while anyway! Even better if you happen to be snaffling the H22a type S out of a JDM front cut – you’ll have all the parts you need right there!

    Finally, read over this writeup thoroughly, research JRC’s site thoroughly, familiarise yourself with any manuals you may have, and ask questions before you start. Attempt to understand every aspect of the system, how and why it works and what exactly is getting replaced by what. Arm yourself with the confidence to tackle the project and you won’t need to look back.

    OK, here we go!

    PREPARE THE CAR

    1) Have the airconditioning refrigerant emptied by a professional. Many auto electricians also work on automotive air conditioning and they should be able to do this for you. The older refrigerant, R12 is a chloro-fluoro-carbon and the newer one, R134a is a hydro-fluoro-carbon. They have been accused of damaging the ozone layer and contributing to the “greenhouse” effect respectively. Consequently the release of either of these into the atmosphere is illegal – DON’T DO THIS AT HOME!!!

    2) Position the car. When you are ready to start working on the car, make sure you park it in a location where it will be comfortable and safe for you to work on, especially considering it may be off the road for a week or more. You will need to be able to get underneath the car to remove and refit one of the heater hoses so if you are using ramps, drive the car onto these now – you won’t be able to drive it later on! I made the mistake of parking the car directly underneath the manhole in my garage ceiling where the ramps are kept so I couldn’t get them out – DUH!

    REMOVE THE CENTRE CONSOLE

    3) Remove the centre console. Remove the two screws above your stereo and the six screws (I think) along both sides of the console and you’ll be able to lift it upwards and towards you. Let the top part “hinge” clear of the stereo before pulling it away.

    4) Undo the gear-shift boot. There are two screws on the underside of the centre console holding the boot in place. Remove these and unclip the boot when you have enough clearance to get under the console. The console should then lift up and you can remove it from the vehicle.

    REMOVE THE STEREO

    5) Remove the stereo assembly. There are four screws holding it into the frame, remove these and support the weight of the assembly as you remove the last one. Place the car in reverse or 4th to get the shifter out of the way and you can pull the assembly out towards you.

    6) Disconnect the stereo assembly. You may have an aftermarket headunit in which case you’ll know what to do here. With the assembly just clear of the frame you should be able to get your hand in and disconnect the stereo loom, antenna coaxial cable and any other wiring you may have back there.

    7) Disconnect the cigarette lighter connector. This is a light grey plug with about 4 wires in it. You can then lift the stereo assembly clear of the frame and remove it from the vehicle.



    REMOVE THE CLIMATE CONTROL UNIT AND AIR VENTS

    8) Disconnect the wiring. Reaching underneath the old climate control unit, you’ll see two connectors towards the right handside. One of these will be a light grey colour and the other is brown with some thicker wires. The brown one goes directly to the blower motor and resistor block to control the fan speed, and the other connector controls the vent modes, recirculation mode, demister and air conditioning, as well as providing power to the unit and the lights on the unit’s panel. Disconnect these plugs and let the harness drop away from the unit.



    9) Remove the old climate controller. There are two screws at the front of the unit below the bottom corners, remove these. There is also a single screw underneath and towards the back of the unit. You’ll need to get in there with a short Phillips head. Gently pull the whole assembly towards you and you’ll feel the clips let go.

    10) Detach the cable. On the left side of the unit a cable comes out. This cable attaches to the heater unit to control the air mix. You should be able to get a screwdriver in on top of the unit once it’s out a little to remove the clip holding the cable and pop the end of the cable off its post. Tuck the cable away and you can pull the assembly out.






    REMOVE THEDASHBOARD

    11) Remove the glovebox. There are eight screws holding the globe box in. One is under the cover on the left end of the dash, another is on the left end bottom corner of the glove box panel. Then there are two on the right hand end. Finally, open the glove box and you’ll see four screws just inside the lid. Once the screws are out you’ll need to lift it clear of one clip.

    12) Remove the driver-side knee bolster. This is held in by four screws and one clip. Pull it free of the coin tray.

    13) Remove the air duct underneath the steering column. This duct runs from the heater unit in the middle to the vent hole to supply the driver door with air. If you pull the two connectors that are anchored in the duct wall you should be able to wiggle it out and remove it.

    14) Remove the steering column covers. There are 4 screws underneath that hold the top cover to the bottom cover and a further 3 that hold the bottom cover to the steering column. The top cover has a couple of clips that will spring loose with a slight upwards pull and then it will come loose from the bottom cover. The bottom cover will need to be manoeuvred around the keyhole and then the tilt adjust lever, then it will pull free.

    15) Drop the steering column. Undo the two bolts and two nuts that secure the steering column to the frame and carefully lower it to the floor.

    16) Disconnect the airbags (if equipped). Disconnect the airbags and connect the red connector.

    17) Remove the dash bolts. There are six black bolts in total, two at each end of the dash underneath the little covers, and one on either side of the centre console frame. Remove these and you’ll be able to start pulling the dash assembly free of the front of the car.

    18) Disconnect the dash harnesses. With the dash pulled a few centimetres towards you, you will be able to better see the dash harness connections. There are two light grey connectors on the passenger side in front of the blower motor and two or three (depending on your model) on the driver side near the fuse-box. One of these will be blue and the other(s) grey.

    19) Remove the dash. Slowly and carefully lift the dash assembly upwards and towards you to clear the windscreen pillars. Then tilt it towards you to manoeuvre it past the contours in the shift linkage tunnel and avoid the rear view mirror. When you get it onto the seats you can then remove it out of either door. It is more awkward than heavy so be careful.





    REMOVE THE AIR CONDITIONING EVAPORATOR

    20) Disconnect the pipework going through the firewall. I need to again emphasise that the release of CFCs or HFCs into the atmosphere is illegal. The greenhouse gas effect that your a/c gas will have on the environment is equivalent to 1.5 tonnes of CO2. Get it professionally emptied! Using a spanner (I used a shifter so I’m not exactly sure of the sizes), remove the lock nuts joining the pipes in the engine bay with the ones passing through the firewall into the evaporator. Start with the small one so that you can get it out of the way for the large one.




    21) Clear the rubber grommet. The pipes going into the evaporator are sealed into the firewall with a rubber grommet. Use a flat blade screwdriver to push the edges of the grommet into and through the hole in the firewall.

    22) Undo the screws/bolts/nuts. Working on the inside of the cabin, you will see four black screws along both edges of the evaporator unit. Undo these with a Phillips head screwdriver, then use a 12mm socket to remove the two nuts at the bottom of the evaporator. Finally, thereis a single gold bolt at the top of the evaporator securing it to the cabin side of the firewall. Use a largePhillips head screwdriver or a 14mm socket to remove this.



    23) Remove the evaporator unit. You should now be able to pull the unit towards you and slightly upwards to clear the drainpipe. Remove it from the vehicle.







    NOTE: The air conditioning system is filled with an oil that lubricates the compressor. Degassing the air conditioning does not remove this oil and you will find some oil in the evaporator. So as you remove it be careful not to drip oil all over your floor. Place the pipe tips over a drip tray or a thick stack of newspaper, and be wary of dripping oil every time you have to move the evaporator.



    REMOVE THE BLOWERMOTOR ASSEMBLY

    24) Disconnect the blower motor from the harness. There are three connectors you will need to undo. One is a brown plug that connects to the resistor box on the front of the blower motor assembly. The second is a small plug that goes into the motor to control the recirculation mode. The final connector has two thick wires going into the bottom of the motor.

    25) Remove the passenger side kick panel. You will find it much easier to get the motor out if you remove this, and you need toget under the carpet later on anyway. Pull the skirt trim up and away first. This is the plastic piece in the frame of the door running for most of the length of the bottom of the door frame. Now, pull the top of the kick panel trim towards you. There is a strong clip that pins this against the rubber in the frame just to the left of where the dash was. Then you can wiggle the front bottom part free of a stud and pull the panel outwards towards you.

    26) Remove the blower motor. There are two gold bolts that you can remove with a large Phillips head or a 14mm socket, and one 12mm nut. The motor should then just come straight out.





    REMOVE THE HEATER UNIT

    27) Drain the coolant. Because the heater uses the heat from the coolant when the engine is at temperature, there will be coolant in the heat exchanger in the heater, and coolant in the hoses connecting the heater unit to the engine’s cooling system. So, get your drain tray underneath the front of the vehicle and remove the drain plug. If you leave the radiator cap in, the coolant will drain more slowly which will prevent it from splashing all over the crossmember and then your garage floor. When the flow starts to fade, remove the radiator cap.

    28) Remove the air intake. You may be thinking,“why?” Trust me, this will give you much easier access to the heater hoses behind the throttle body. I won’t go into specifics here because many of you will have cold-air intakes, short ram intakes or even turbo setups. But whatever you’ve got, the aim is to give you some working space.

    29) Remove the brackets on the firewall behind the throttle body. JRC recommends removing these and it certainly would have made my life a lot easier but I could not get the nuts off– so they stayed! You can work around them if you need to but try to take off the one holding the MAP sensor, and the bracket below it that holds the water valve and cable.

    30) Remove the water valve cable. From the driver side of the bracket, you should be able to pop the clip holding the cable tube upwards from underneath. With that free you can lift the end of the cable off the post in the valve.



    31) Position your drain tray. In the next step your heater hoses will be coming off. They will be full of coolant so get your tray under the car in this spot. In hindsight I should have got an oil funnel to help drain this coolant away so that it did not splash around on the steering rack before dripping into the tray.

    32) Remove the heater hoses. Squeeze the clips and pull them along the hoses towards the front of the vehicle so you can clear the area where the hoses join the pipes. Now, if you can remove these hoses easily and without damaging them you’ve done very well. For those of us not regularly in the habit of performing miracles, the quick way is to get your Stanley knife and cut the hoses along their length from the end to just past the end of the pipe (you should be able to feel where the pipe ends, the hoses will be more flexible here). I wasted nearly two hours trying to free the hoses without damaging them and got absolutely nowhere, so if you don’t have the time to waste and you’re just itching to start playing with the new parts – then bite the bullet and cut the hoses off. Of course, if you cut them you’ll have to replace them with the new ones you should have already ordered (you did, didn’t you?) This means you’ll need to remove the other ends of the hoses too but we’ll get to that later.

    33) Plug the copper pipes. Man, I wish I’d done this! I thought it would be sufficient to stuff some thick rags into the ends of the pipes to soak up any stray coolant. There turned out to be more stray coolant just brimming at the tips of those pipes than my makeshift sponge could handle and I had to mop coolant up off the footwells after removing the heater unit!! Whatever you use to plug these pipes, make sure that it will fit inside the ends of (or at least flush with) the pipes so that the plugs don’t get pulled off when you drag them through the firewall.

    34) Prepare the heater unit for removal. Looking at the engine bay side of the firewall, find two bolts with nuts securing them. They are about 5cm below the level of the heater hoses and about 10cm to either side. You’ll need a 12mm spanner to get these nuts off – I couldn’t for the life of me fit a socket wrench in there so spanner was the go. Once these are free you’ll need to step into the cabin and remove the two gold bolts at the top of the heater unit. You can use a large screwdriver for these or a 14mm socket – the screwdriver was easier. As these come out – be careful! The heater unit will tilt down towards you and if your bungs aren’t nice and tight you might start to spill some coolant. Since the heater unit is all but out, you can manoeuvre it slightly to get at the clip underneath that holds the cabin-side end of the water valve cable in place. Remove the cable from this clip and remove the end of the cable from the pole.

    35) Remove the heater unit. If you didn’t dislodge them in the last step,the only thing that will provide resistance as you try to pull the heater unit out is the rubber rings around the copper pipes passing through the firewall. Pull the whole unit towards the back of the car, keeping the direction of pull as horizontal as possible. Once the pipes are free of the firewall you can remove the heater unit from the vehicle but keep in mind that if anything happens (or did happen during the aforementioned pulling) to your bungs then you will have coolant everywhere.





    WIRING THE NEW HARNESS

    After the last step you’ve probably taken a look around and seen bits and pieces of your car everywhere! Don’t be discouraged, it’s all part of the process – now we can get into the nitty gritty!

    Forgive me for talking to the lowest common denominator here, but if you don’t have a lot of experience with a soldering iron I’ve included this brief guide to help you get the best results you can. Obviously if you’re a seasoned super solderer (Triple S for short) you can skip this:

    a) Get your soldering iron ready. Run an extension cord to roughly where you will be working and plug in your soldering iron, making sure you keep the iron in a safe place while not in use (in a soldering stand or something) and well away from being able to melt through your power cables. Switch it on and let it heat up. If you have a temperature controlled iron, then anywhere between 180 and 300 degrees will be fine depending on your solder (check your solder packaging for recommendations).

    b) Clean the iron tip. After spending a few minutes at the desired temperature, the tip of the iron will start to blacken.This residue will contaminate your solder joints and “soak up” the heat from the tip, making it more difficult to make a joint “take”. So clean the tip before EACH use. Use a wet sponge or something to do this, many soldering stations have a sponge pad built in for this purpose.

    c) Prepare your wires. Identify which wire you need to solder and what you’re soldering it to. In this project, you will be clipping off your old connector and soldering the tails from the new JDM connector to the wires in the loom, as well as a few other connections at various locations. It is best to only clip one wire at a time from the old connector to assist you in identifying your wiring. Where you need to run a new wire, get out your hookup wire and make sure you have enough length before you start cutting anything. Be aware of the path that wire will have to trace so you know exactly where it will go and how long it needs to be.

    d) Trim your wires. When you are ready, cut the wire to expose the loom. Use a wire stripper (or a Stanley knife) to trim 5-7mm of the insulation from both the loom wire and the new connector tail. I use some photos of the VSS wire near the ECU here to illustrate:



    e) Tin the wire tips. Use your fingers to twist the newly exposed wire. This will keep the tips nice and neat and prevent stray strands from poking out in all directions. Now after cleaning the soldering iron tip, hold the iron against the exposed wire. Copper is an excellent electrical conductor which is why we use copper wires. Unfortunately copper is also an excellent conductor of heat. As you heat the end of the wire, heat will transfer along the cable so you may want to use a pair of pliers or a proper soldering clamp to hold the wire 5-10 cm from the end. As the tip of the wire approaches the melting point for your solder you should be able to touch the end of your solder onto the wire and let the wire “absorb” the solder. A resin in the solder helps the solder to bind the wire strands together so that eventually you have covered the wire and filled the gaps between the strands. This process is calling “tinning”. If you cannot get the solder to do more than just stick to the outside of the twisted strands then you probably don’t have enough heat in the iron tip. This is an acquired skill: don’t let the wire become “blobby” with solder everywhere, but give the wire enough solder not to leave any copper exposed.



    f) Prepare the heat shrink tubing. Select some heatshrink that will fit easily over the gauge of wire you are working with and cut off a section about 1.5 – 2.0cm long. Looking at the two wires you have to join, choose which end has the longer tail – this will keep the heat shrink clear of the end as you join the wires in the next step, preventing it from shrinking before we want it to. Ideally try to give it at least 5 cm. Once the end of your chose wire is cool enough to touch with your fingers (30 seconds should be enough) slide the tubing over the end and down the wire.

    g) Join the wires. This bit takes some practise and you may need to use more than one clamp. Clean your iron tip again. Then dab a small amount of solder onto it – this will help solidify the gap between the two wires. Position your wires so that they meet end to end and allow them to overlap so that the exposed, tinned tips are sitting side by side. Manoeuvre the wires to keep the tips side by side as you heat them up. Place the soldering iron tip against BOTH of your wire tips to heat them simultaneously. It’s a good idea to place the iron tip underneath the wires so you can easily see the wires. As they heat up, their solder will begin to melt into the solder of the other wire, augmented by the extra solder you have on the iron tip.



    h) Allow the wires to cool. Once they have made a good connection and covered the strands of wire on both sides, remove the iron and allow the wires to cool. You may need to hold the wires together to keep them from moving for 5 seconds before the solder cools and solidifies. WARNING: it is during this cooling phase that potential dry joints are formed. Not so critical in joining wires together as when you’re soldering onto a PCB (printed circuit board), but even the slightest movement of the wires as the solder cools can introduce small air pockets in the solder which may develop into hairline cracks with the added stress of uneven cooling. These cracks may eventually compromise the electrical connectivity of your solder joint – a “dry” joint. The moral here is to hold the wires very steady until you can see the solder solidify (the surface will go from a silvery mercury-looking surface to a dull silver in need of a polish).

    i) Test the connection. What you’re looking for here is not the electrical conductivity of the connection, but the physical strength. Firmly but gently pull the wires apart. If there is ANY movement in the joint then you’ll need to do it again.

    j) Shrink the tubing. Once the joint has cooled down sufficiently (again, 20-30 seconds will do it) slide the heat shrink tubing along and centre it over the joint. Use a heat source to shrink it, a hair dryer or a heat gun works well as it will shrink the tubing uniformly but careful not to burn yourself with the hot air. Make sure that the tubing cannot move along the wire. If it can, you either need to shrink it more, or you have chosen tubing that is too big and won’t shrink any further.





    k) Admire your handiwork. The area around the join will still be hot to the touch after you’ve shrunk the tubing onto it. While it cools, make sure that there are no sharp chunks of solder poking through the tubing and that the whole join is not too bulky. You will have 30 or so of these sitting side by side in your new harness!

    Okay, with that bit of housekeeping out of the way, let’s get into the details! The AUDM harness consists of two connectors, the green 16-pin one and the brown 6-pin one. When I talk about the AUDM connector below I refer to the 16-pin unless I specify otherwise.

    The JDM harness has two similar connectors, one 16-pin andone 20-pin. Take a look at the diagram to clarify what each connector does.







    Power Wires

    36) Connect the #8 (Black/Yellow) wire from the AUDM connector to the #13 wire on the 20-pin JDM connector. This is the 12 volt supply from your ignition.

    37) Connect the #13 (Black) wire from the AUDM connector to the ground wires on both JDM connectors. These are #10 on the 16-pin and #16 on the 20-pin and they are both black.

    38) Connect the #11 (White/Yellow) wire on the 20-pin JDM connector to a source of constant 12 volts. This wire is for memory and is used to recall your climate control settings every time you switch the car on. The easiest source for this constant source is the memory wire for your stereo (usually Yellow).

    39) Connect the #6 (Red/Black) wire from the AUDM connector to the #2 (Red/Black) wire on the 16-pin JDM connector. This is the dimmer control wire, which dims your display at night.

    Rear Window Defrost

    40) Connect the #10 (Yellow/White) wire from the AUDM connector to the #14 (Yellow/Green) wire on the 16-pin JDM connector.

    Mode Control Motor

    41) Connect the #3 (Brown/White) wire from the AUDM connector to the #6 (Brown/White) wire on the 16-pin JDM connector. This sets the mode to windscreen defrost.

    42) Connect the #7 (Light Green/White) wire from the AUDM connector to the #15 (Light Green/White) wire on the 16-pin JDM connector. This sets the mode to vent.

    43) Connect the #9 (Light Green/Red) wire from the AUDM connector to the #15 (Light Green/Red) wire on the 20-pin JDM connector. This is the ground for the mode control motor.

    44) Connect the #14 (Blue) wire from the AUDM connector to the #7 (Blue) wire on the 16-pin JDM connector. This sets the mode to footwell heat/windscreen defrost.

    45) Connect the #15 (Blue/Red) wire from the AUDM connector to the #8 (Blue/Red) wire on the 16-pin JDM connector. This sets the mode to footwell heat.

    46) Connect the #16 (Yellow/Green) wire on from the AUDM connector to the #16 (Yellow/Green) wire on the 16-pin JDM connector. This sets the mode to footwell heat/vent.

    Recirculation Control Motor

    47) Connect the #4 (Green/Red) wire from the AUDM connector to the #13 (Green/Red) wire on the 16-pin JDM connector. This sets the mode to recirculate.

    48) Connect the #11 (Green/White) wire from the AUDM connector to the #5 (Green/White) on the 16-pin JDM connector. This sets the mode to fresh.

    Air Conditioning

    49) Connect the #1 (Blue/Red) wire from the AUDM connector to the #1 (Blue/Yellow) wire on the 20-pin JDM connector. This is the air conditioning pressure switch line that activates the compressor clutch, engaging the compressor.

    NOTE:

    At this point, all the wires in the original loom running to devices that will be used in the new climate control setup have been used. That is, any wires still connected to a pin on either of the original AUDM connectors (16-pin or 6-pin) will not be used for their original purpose. This means that you can use them for your sensors or air-mix motor wiring. For example, from memory there are some wires that run in the 5-pin connector that end up at the resistor block. You can cut these near where they come out at the resistor block (obviously, check that the colour coding is correct and that you have continuity with a multimeter so that you can be SURE that the wire is the right one) and use them for your evaporator sensor and power transistor base. Connect the evaporator sensor and power transistor base to the freshly cut wires at the evaporator end, and connect the tails in the loom to the appropriate wires in the JDM connector. You WILL need to run new wires to many of the sensors etc, and I would recommend pulling these new wires along the loom and through the loom wrap to keep it all neat.

    Blower Motor Power Transistor & “High” Relay

    The JDM Digital Climate Control unit uses a power transistor to control the fan speed instead of the resistor block. This allows the fan speed to smoothly ramp up and down to the desired setting and achieve speeds in between what would be possible with the resistor block. For those unfamiliar with how a transistor works, it has three connections. These are called the collector, emitter and base. The emitter is essentially a path to ground, allowing current to drain away. In a functional circuit, this pathway travels through the connected load, or the circuitry you are supplying current to. The collector is connected to a voltage source, ready to supply a high current. The base is connected to a low current voltage source. Now, as the current at the base is varied, it controls the current that flows from the collector to the emitter. So imagining this setup in place of the resistor block where each resistor limits the current flowing through the blower motor thus determining the motor’s speed: the control unit supplies a small current to the base, the transistor allows a proportionately larger amount of current flow from the battery through the blower motor to ground. As the climate controller varies the low current to the base, the blower motor’s speed will vary due to the changing current supplied to it from the emitter.

    You may have noticed that the transistor is attached to a relatively large heatsink. That’s because it gets hot! There is a relationship between the amount of current flowing through a conductor, and the amount of heat that conductor will generate dependant on the thermal characteristics of the conductor itself. So the higher the current flow through the transistor, the hotter it will get. To prevent it from getting too hot by operating at full speed for long periods of time, the climate control system comes with a “high”relay. This is basically a relay that short circuits the contacts between the collector and emitter on the transistor, diverting all current flow around the transistor rather than through it. This achieves full fan speed without heating up the transistor.

    You need to decide where you want to mount the relay. The JDM setup has it mounted near the blower motor using one of the screws that hold the recirculation motor in place. I took a look at the wiring diagram for the power transistor/relay circuit that JRC has on his site and decided to mount the relay behind the air vents and controller. Mounting here allowed me to use existing wiring in the climate control harness and kept the wiring neat at the blower motor end. The next few steps will go through connecting the power transistor and relay the way I did it. If you decide you MUST have it in the stocklocation, then you’ll have to consult this diagram and work out how to make your own connections.

    Also, you will notice that the relay I used is not the JDM one. I was not able to source the exact relay without paying a fortune for it on its own so I used a standard 30 Amp headlight relay:





    For the Power Transistor:

    50) Clip the thick Blue/Red wire going into the resistor block. Connect this to the collector on the power transistor. On the three-pin plug on the transistor, the pin that sits alone on top of the other two pins is the collector. You’ve just connected the #1 wire on the above diagram.

    51) Connect the emitter on the power transistor to a ground point using a thick wire. The emitter is the right-hand pin of the remaining two of the plug (looking at the plug so that the collector pin is alone ON TOP OF the other two pins). Any ground point that will give you a reliable connection will do. This is the #6 wire on the diagram.

    52) Connect the base of the power transistor (left-hand pin on the transistor plug) to the #9 (White/Blue) wire on the 16-pin JDM connector. This takes care of the #5 connection in the diagram.

    For the “High” Relay:

    53) Identify the connections on the harness that plugs into your relay. I can’t remember the colour codings as my relay is now tucked away behind my dash. But basically there are four wires, two thick and two normal. Two of these will connect to either side of the relay coil, forming the trigger circuit. The other two connect across the “load” (in this case, the blower motor) with the relay contacts acting as a switch between them. Since relays use a low-current trigger circuit to switch a high-current load circuit, the two thick wires going into the relay will be for your load and the two normal-sized wires will connect to the relay coil. Another thing to note about relays is that neither the trigger circuit nor the load circuit are polar, since neither the coil nor the “switch” have a polarity. This means as long as you connect to a thick wire for the load, and a normal wire for the trigger circuit, you can’t go wrong – it doesn’t matter which thick or normal wire you choose.

    54) Connect one side of the relay coil to a 12V source that is switched by the ignition. The #13 (Black/Yellow) wire on the 20-pin JDM connector is a good one to splice into for this. You’ve just connected the #2 wire on the diagram.

    55) Connect the other side of the relay coil to the #3 (Blue/Orange) wire on the 20-pin JDM connector. This is the #4 connection on the diagram.

    56) Clip the thick Blue/Red wire on the brown 6-pin AUDM connector. Connect this to one side of the relay’s load circuit (thicker wires, remember?) That’s the #3 connection on the diagram out of the way.

    57) Clip the thick Black wire on the brown 6-pin AUDM connector. This runs to ground which is where the other side of the load circuit on the relay needs to go to. So connect this to the remaining wire on the relay and you’ve taken care of the other #6 connection on the diagram.

    Air Mix Motor

    One thing to note about the air mix motor and the sensors is that they all have a Light Green/Red wire. This is a ground wire and is common between all the sensors and the motor. It is advisable to bring the #17 wire (also Light Green/Red) on the20-pin JDM connector down the loom (to save bunching multiple cables through the end of the harness) and making it available as a common connection point before wrapping these joins in some electrical tape for insulation.

    Hopefully these pictures will give you an indication of where the wires will need to end up, helping you plan your wire lengths.

    58) Connect the Red/Yellow wire on the air-mix motor to the #4 (Red/Yellow) wire on the16-pin JDM connector. This steps the motor towards the HOT side.

    59) Connect the Red/White wire on the air-mix motor to the #12 (Red/White) wire on the16-pin JDM connector. This steps the motor towards the COLD side.

    60) Connect the Grey wire on the air-mix motor to the #7 (Grey) wire on the 20-pin JDM connector. This supplies a potential of -5V to the motor.

    61) Connect the Pink/Black wire on the air-mix motor to the #8 (Pink/Black) wire on the 20-pin JDM connector. This supplies a potential of +5V to the motor.

    62) Connect the Light Green/Red wire to the #17 (Light Green/Red) wire on the 20-pin JDM connector. This wire shares a common ground with all the sensors.

    Sensors

    Before we start wiring the sensors, first consider where the sensors will be located and how we will get the wires there.

    The location of the sunlight sensor should be obvious – our poor AUDM ludes have had to be content with a blanking plate near the windscreen glass in front of the driver end of the dash. The shape of the plate should be a huge hint as to which of your sensors goes in there. With the dash out, you can fit the sensor into the hole left by the blanking plate and observe how the connector sits with the wires coming out towards the driver side of the car. You may be lucky enough to have one of those little brown button-hole clips on the wires. Look for the small hole near the sensor where this clip pushes in. Now your wires will need to run down the pillar (I cable-tied mine to the dash loom that runs down this side) and then to your centre console area to meet the climate control harness along any path of your choosing.



    The outside air temperature sensor mounts on the outside (DUH) in front of the radiator. There are a number of locations that would be adequate but keep this in mind. You don’t want direct air from the grill blowing across the sensor or this would give you a false reading. You also don’t want the sensor in a dead spot where engine heat builds up. I located mine near the right-hand headlight, using one of the headlight bolts to secure it to the vehicle body. From there, I ran wires into the engine bay behind that headlight and strapped them into the loom that runs alongside the battery, up the right strut tower and into the fuse box. Behind the fuse box is a rubber seal that you can push the wires into the cabin through. These will appear in the driver footwell near the cruise control computer and from there you can take them across to the climate control harness.







    The evaporator temperature sensor is quite easy, as I mentioned before you can use two of the redundant cables from the old harness to plug across this sensor.



    The heater core temperature sensor is also easy, these wires will need to run to the same location as your air-mix motor.



    The cabin temperature sensor fits into the dash, in the blank-plate filled cavity between the vents and the steering column. It should be easy enough to get your wires from this sensor down the side of the centre console frame to meet the climate control harness.



    63) Vehicle Speed Sensor (VSS). Connect the #5 (Orange) wire on the 20-pin JDM connector tothe VSS wire. This wire is orange and can be found at the ECU harness (pin B10 On OBD1 ECUs, see the below diagram). Since the wire also runs to the instrument cluster for the speedometer, you can trace it through the loom and splice into it at a point near the climate control loom if you wish. I found it easier to run a separate wire from near the ECU connector and strapped this into the loom.



    64) Cabin temperature sensor. Connect the #18 (Brown/Red) wire on the 20-pin JDM connector to the Brown/Red wire from the cabin temperature sensor.

    65) Evaporator temperature sensor. Connect the #9 (Brown) wire on the 20-pin JDM connector to the Brown wire from the evaporator temperature sensor.

    66) Outside air temperature sensor. Connect the #19 (Brown/White) wire on the 20-pin JDM connector to the Brown/White wire on the outside air temperature sensor.

    67) Sunlight Sensor. Connect the #10 (White/Red) wire on the 20-pin JDM connector to the White/Red wire on the sunlight sensor.

    68) Heater core temperature sensor. Connect the #20 (Pink) wire on the 20-pin JDM connector to the Pink wire from the Heater core temperature sensor.

    69) Sensor Ground. Connect the Light Green/Red wires from all sensors (except the Vehicle Speed Sensor) to the #17 (Light Green/Red) wire on the 20-pin JDM connector via the common ground point shared with the LightGreen/Red wire from the air-mix motor.

    Water Valve Solenoid



    If you have managed to get hold of the proper JDM water valve solenoid, you’ll probably want to hook that up, right? There are two wires connected to the solenoid and these wires need to get through the firewall like the outside air temperature sensor wires did. You can either use the same access point or there is one on the passenger side underneath the bunch of connectors in the engine bay there. From either one you will need to get the wires across to the water valve. I cheated and punched the wires through the rubber grommet that seals around the water valve cable. This comes through above your left foot near the clutch pedal.

    70) Connect the Brown/Black wire from the solenoid to the #2 (Brown/Black) wire on the 20-pin JDM connector. This is a switched path to ground which activates the solenoid.

    71) Connect the Black/Yellow wire from the solenoid to the #13 (Black/Yellow) wire on the 20-pin JDM connector. Since this is already connected to ignition-switched power supply, you will need to splice into this connection. This will supply the solenoid with 12V in readiness for activation by the wire you hooked up in the previous step.

    CLEANING & GENERAL MAINTENANCE

    Okay, now that you’ve got your wiring ready I bet you’re itching to start plugging it in and putting it back together. Spare an hour or two to clean up some of your parts before jumping in at the deep end though…

    72) Clean your evaporator. When you pulled your evaporator out and put it on your garage floor you may have noticed that there were all sorts of dead bugs, leaves, twigs, fluff and maybe some bird feathers stuck in the opening on one side. When the recirculation mode is in “Fresh” the blower motor sucks air in from the fresh air intake in the plastic hood underneath the lip of the bonnet on the passenger side. Doesn’t take an Einstein to figure out that you WILL get some rubbish down that intake every once in awhile. The blower motor then does a stellar job of throwing it at the evaporator. You may have so much blockage happening on the blower side of the evaporator that you find you get much more air blowing after you clean this out! There are a couple of screws, several U clips, and some black sponge strips that hold the two sides of the evaporator housing together. Get these out of the way (remove the sponge carefully and it should still be clean/intact enough to reuse) and you can pry the shell apart. Then pull the evaporator core out and clean the inside of the shell and the Styrofoam case with a vacuum cleaner and a soft-bristled brush. Now turn your attention on the evaporator itself. Obviously vacuum it from the blower side so you don’t suck anything even further in between the fins. Be careful not to bend the fins too much. They will bend back but might break or flake in the process. The fins don’t actually carry any refrigerant through the evaporator, they purely provide surface area to disperse the“coldness” from the pipework in the evaporator – so don’t worry too much if you do end up bending or even breaking off small pieces. Once this is all clean to your satisfaction, don’t be too hasty in putting it back together because you’ll need some clearance between the halves of the outer casing to swap the thermostat with the sensor. In other words, reassemble it but leave the clips and screws off.







    73) Clean and check your blower motor. If you have had any issues with the blower motor at all (ie steady decline in performance, grinding noises etc) then it would be worth taking it to an auto-electrician. They can check the impedances on the windings, lubricate the spindle and maybe even recondition the motor with new brushes etc. The housing that the motor sits in will do well to have a good clean as it will mostly likely be coated with graphite dust and all manner of other grime inside and out.

    74) Clean and drain your heater unit. The heater unit has several vent doors inside that control the flow of air through it. These doors have a spongy padding which may have perished and will crumble to the touch depending on their age. For this reason I pretty much left the inside of the unit alone definitely staying well clear with the vacuum cleaner. But you may want to clean any dust and debris off the outside of the unit. At this point it would be a good idea to flush the remaining coolant from the system too. Remove your bungs and let it drain into the drip tray containing the rest of your coolant. With the pipes facing downwards slowly rotate the unit through 90 degrees on either side of that position to let the pockets of coolant inside drain out. I then blasted the core with some water pressure to remove sediment and other muck. Just take the plastic fitting off the end of your hose and the hose itself should fit squarely (or roundly) against the mouth of one of the pipes. Give it some pressure in both directions (on both pipes alternatively) to dislodge whatever might have been sitting at the bottom of the core for the last 10 years or more and when the water coming out is as clean as the water going in, repeat the above procedure to drain the water from the heater core.

    REASSEMBLY

    Blower Motor

    75) The only change made to the blower motor for this conversion is the installation of the power transistor in place of the resistor block. Undo the two screws holding the resistor block bracket into the blower motor housing and remove the resistor block.



    76) Drop in the power transistor assembly and do the screws back up. The power transistor and, in the old setup, the resistor block are both mounted in this location to allow them to keep cool in the airflow.



    77) Reverse steps 24– 26 to reinstall the blower motor.

    78) If you’ve chosen to locate the “high” relay in its stock location, now is a good time to do that.

    Air Mix Motor/Heater Core Temperature Sensor

    JRC devotes considerable attention to this part but this is because the USDM Prelude is build “backwards”. Since they are a left-hand drive vehicle and there is no room in the driver side footwell for the blower motor and evaporator as well as the pedals and steering column, Honda had to build the heater unit, blower motor assemble and evaporator in mirror image for the USDM and install them in the passenger (right hand side) footwell. Now with the air mix motor from the JDM models being designed for right-hand drive cars it will work backwards if installed in the USDM model. For this reason JRC had to be quite inventive to get it working correctly.

    We are lucky however, to be driving on the left-hand side of the road while sitting in the right-hand seat – just like our Japanese buddies. So Honda put the exact same parts in our AUDM lude as what is found in the JDM model in terms of the heater unit etc. What I’m saying is that the air mix motor will screw straight into the heater unit and work properly without any modification! You will even find a little notch in the carpet just to the passenger side of the centre console (against the firewall) where the wires for the air mix motor and heater core sensor come up from the loom!

    79) Flip the heater unit upside down and locate the plastic panel on the bottom passenger side end.






    80) Unscrew this panel.

    81) Place the bracket holding the air mix motor (with the wires protruding from the edge of the unit) over the mounting holes and screw it in.



    82) The curved arm on the air mix motor replaces one of similar shape already fitted to the heater unit assembly. Locate and remove the old one and fit the rod to the plastic clip on the air mix motor arm.

    83) Slide the heater core temperature sensor into the convenient little slot that Honda made for us.



    84) Replace the plastic panel that you removed in step 80

    85) Note the post on the air mix motor arm. When you reinstall the heater unit, one end of the water valve cable will need to attach to this post unless you have installed the JDM water valve with its solenoid.

    Cabin AirTemperature Sensor Snorkel Tube

    This black tube is in two halves: one half has the strange basket looking thing (called the “aspirator unit”) at the end and the other half is attached to the sensor itself. The two halves clip together in the middle. The half with the basket attaches to the side of the heater unit around the vent mode motor.

    86) Place the heater unit on its side so that the vent mode motor is on top.

    87) Locate the mounting point for the end of the snorkel tube – it is circular, about the size of a 20 cent piece, and has two holes for screws on either side of it.



    88) You may need to file the plastic bit in the middle down or clip it with a pair of wire cutters so that the aspirator sits neatly over the top.

    89) Screw in the aspirator. The tubing should shape around the vent mode motor and hug the side of the heater unit.





    Heater Unit

    90) If you won’t be using the JDM water valve and solenoid, you’ll need to connect the cabin end of the existing heater valve cable to the post on the air mix motor that I mentioned back in step 85. This might prove fiddly and there’s no secret to it. Use needle nose pliers, flat blade screwdrivers on their side – whatever you can. If I did it, so can you!

    91) Reverse steps 34 and 35 to reinstall the heater unit.

    92) With the heater unit in place, you can now connect the wiring harness you made for the air mix motor and heater core temperature sensor.

    Evaporator Unit

    93) Your evaporator should still be accessible from step 73. You will see on one side of the evaporator core the air conditioning thermostat wedged in between the fins. Remove the thermostat by prying the covers apart just enough to free the thermostat stem and gently pulling the probe out from between the fins.





    94) In place of the thermostat, fit the evaporator temperature sensor. The white clip will push down between the fins and hold the sensor in place just above the surface of the core.

    95) Run the sensor harness over to the hole left by the thermostat grommet and fit the sensor grommet to this hole.



    96) Refit any of the black sponge strips that may be loose, and do up the screws and clips making sure that the pieces of the evaporator unit fit neatly together without applying excessive force.

    97) Reverse steps 20- 23 to replace the evaporator unit. In this process I found it useful to have the gold bolt at the top inside the cabin loosely fitted so that it sat at the end of its travel. Leave the other screws and nuts till later. Holding the evaporator up with this single bolt will give you enough clearance between the evaporator and the firewall to coax the big grommet surrounding your evaporator pipework back through the firewall. Careful though as this grommet will tear easily. Once this is through, you can safely do everything up.

    98) Now you can attach your new wiring to the sensor connector at the evaporator.

    99) Short-circuit your air conditioning thermostat. You won’t need the thermostat any more since the evaporator temperature sensor will allow the climate controller to perform the same task electronically. The thermostat is basically a mechanical cut-off switch activated by low temperatures to prevent the evaporator core from becoming too cold. Of the two wires going into the connector for the thermostat, one of them comes from the controller with a supply of 12 volts (provided that the controller has activated the a/c function), and the other goes to the compressor. The thermostat prevents the compressor from operating when the evaporator core is below its threshold temperature by simply cutting out the connection between these two wires. So, to enable your air conditioning you need to connect these two wires together. I traced them back to where they disappear into the loom and spliced them together.



    NOTE: If you do NOT perform step 99 then there is no chance your air conditioning will ever work! This is not mentioned in the JRC writeup, but I hope the explanation given here helps you understand why this step is crucial to the operation of the air conditioning compressor.

    Dashboard

    100) Reverse steps 11– 19 to replace the dashboard.

    Climate Control Unit and Air Vents

    101) If you haven’t already done so, remove the old climate control unit from the vent frame and replace it with the new digital unit. You should find this straightforward.

    102) Reverse steps 8 and 9 to replace the controller and vents, connecting your newly modified harness to the bottom of the digital control unit.

    Stereo

    103) Reverse steps 5 – 7 to replace the stereo unit and cigarette lighter.

    Centre Console

    104) Reverse steps 3 and 4 to replace the centre console.

    Regas theAirconditioning System

    105) As mentioned at the beginning of this writeup, it is likely that you will need to convert the airconditioning system to the newer R134a refrigerant gas if you have not already done so. There is nowhere that the R12a refrigerant is still legally available so this conversion is unavoidable. Shop around for the best price though, making sure that the conversion includes replacing all the seals and other components to make them compatible with the R134a gas, and of course includes the regassing with the new refrigerant. You will know if this has (already) been done as the old R12a system had white high/low manifold valves whereas the new R134a system will have a red valve on the high pressure side of the system, and a blue valve on the low pressure manifold.





    TEST THE SYSTEM

    106) If everything has gone to plan you should now have a fully functioning JDM digital climate control system installed in your car! Test each function though to make sure that it all works properly before getting too excited. Pay particular attention to the operation of the airmix and mode control motors, and the water tap on the engine side of the firewall. Setting the HI and LO temperatures will automatically open and close this tap respectively so that will be a good way to see it in operation and to make sure that the cable is functioning (or the solenoid, should that be installed). Also, test turning the AC on and off to make sure that you can feel the compressor engaging and disengaging (obviously you will need to have the engine running for this). If anything is not as it should be, go back over the steps in the relevant section and make sure that the instructions have been followed. You may need to use a multimeter to troubleshoot the modified wiring and make sure that all is correct there before turning your attention to the other components.

    ENJOY!!!

    You can probably see now that I meant it when I said this is not a small project. If you have completed the job, well done!! Give yourself a pat on the back – you deserve it! I found it immensely rewarding to have successfully finished the project, quite apart from the novelty of having digitally controlled blowing air and the JDM cred that came with it.

    Now, throw away that empty box and find something else to store on your dusty shelf … JDM folding mirrors perhaps?








    The path of Honda is beset on all sides by the iniquities of Mazda and the tyranny of Nissan. Blessed is the Honda owner who in the name of handling and performance shepherds his Honda through the valley of darkness, for he is truly his Honda's keeper and the finder of lost kilowatts. And I will strike down upon thee with great acceleration and furious VTEC those who attempt to overtake and destroy my Hondas. And you will know my name is PRELUDE when I lay my VTEC upon thee.


  2. #2
    QLD Administrator AdReNaLiN's Avatar
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    Great writeup Shane! Great to see such an excellent guy back on the forum.

  3. #3
    Senior Member Sean628's Avatar
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    I think we need a wiki page for this

  4. #4
    Silver Member Seismic's Avatar
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    Quote Originally Posted by AdReNaLiN View Post
    Great writeup Shane! Great to see such an excellent guy back on the forum.
    Thanks Steve! I'm only sorry I didn't have this to hand when you needed it for your conversion
    The path of Honda is beset on all sides by the iniquities of Mazda and the tyranny of Nissan. Blessed is the Honda owner who in the name of handling and performance shepherds his Honda through the valley of darkness, for he is truly his Honda's keeper and the finder of lost kilowatts. And I will strike down upon thee with great acceleration and furious VTEC those who attempt to overtake and destroy my Hondas. And you will know my name is PRELUDE when I lay my VTEC upon thee.


  5. #5
    Silver Member curtis265's Avatar
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    WOW

    talk about some crazy effort!

    mad props!
    ¡uoǝbunp ǝɥʇ oʇ
    グ-ビ ください

  6. #6
    Silver Member Seismic's Avatar
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    The conversion, or the writeup? The writeup took me just as long I think! LOL
    The path of Honda is beset on all sides by the iniquities of Mazda and the tyranny of Nissan. Blessed is the Honda owner who in the name of handling and performance shepherds his Honda through the valley of darkness, for he is truly his Honda's keeper and the finder of lost kilowatts. And I will strike down upon thee with great acceleration and furious VTEC those who attempt to overtake and destroy my Hondas. And you will know my name is PRELUDE when I lay my VTEC upon thee.


  7. #7
    Gold Member Pacman's Avatar
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    Epic Shane is epic....
    I took the other route, bought a JDM..... Easier me thinks...
    But epic effort.... On both the conversion and the write up...
    http://www.preludeaustralia.com/foru..._view&id=12025
    Link to my garage.^^^^

    When words fail, VTec speaks!

    Quote Originally Posted by EXO8IC View Post
    My car is a twin turbo and has a blow valve with another little valve thing attached which silences that WOOSH (which I HATE) but it makes more of a strange sucking noise which can be heard quite loudly from my vents on the bonnet. It's quite odd...

  8. #8
    Silver Member diMii's Avatar
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    --Australia--
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    1,326
    Yeah definitely an amazing write up. Even though I've done this I actually leant heaps of awesome electrical stuff. Props to you

    Ps: if anybody wants to do this I have the complete set for sale

  9. #9
    Senior Member Scotty's Avatar
    Generation
    4th Gen
    Model
    Si turned VTIR
    Join Date
    Feb 2007
    Location
    Queensland
    Posts
    694
    That's an awesome write up Shane.
    Good to see you back!

  10. #10
    Gold Member SnowWhiteLude's Avatar
    Generation
    3rd Gen
    Model
    JDM Si 4WS
    Join Date
    Oct 2006
    Location
    Victoria
    Posts
    2,450
    Intense work right there.


  11. #11
    Silver Member Seismic's Avatar
    Generation
    4th Gen
    Model
    Custom
    Join Date
    Jun 2004
    Location
    Queensland
    Posts
    1,350
    Thanks guys for the feedback. I really am sorry I didn't get around to compiling it all sooner - I know there would have been many who would have utilised it!
    Maybe it will help you get your set sold diMii
    The path of Honda is beset on all sides by the iniquities of Mazda and the tyranny of Nissan. Blessed is the Honda owner who in the name of handling and performance shepherds his Honda through the valley of darkness, for he is truly his Honda's keeper and the finder of lost kilowatts. And I will strike down upon thee with great acceleration and furious VTEC those who attempt to overtake and destroy my Hondas. And you will know my name is PRELUDE when I lay my VTEC upon thee.


  12. #12
    PA Expert ego's Avatar
    Generation
    Non Honda
    Join Date
    Aug 2006
    Location
    Victoria
    Posts
    5,548
    That's some serious commitment there and great write up but it might convince people to not do it rather than to do it =P

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