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    INT: JDM Digital Climate Control

    This is one of those where there is a little info out there but mostly incomplete. With all the threads I searched, I only found one claiming that it was fully installed. Even then there are only pictures of the control unit and none of the other required parts. I debated whether or not to even bother with a write up but ultimately against my better judgement I did it anyways.

    This write up explains most everything in detail but don't go riding off on your unicorns to mystic lands just yet. This a fairly involved process that is time consuming. Expect to give yourself 3-4 days to complete this cleanly. It could be done in a weekend if you want to do a hack job. For complete operation the dash has to come in order to remove the heater unit. While installing the dcc is not overly difficult, it is very involved and beyond the capabilities of the inexperienced. Meaning if you don't understand it, you probably don't have skills required to complete this.

    The 4th gen Accord digital climate control system differs from the USDM system by a few things. Luckily all you need from jdmland is the the controller as the rest of the parts can be sourced from a variety of US cars. As far as wiring goes, there wasn't a cb7 specific diagram that I could find. After about 15 hrs comparing diagrams from various Honda's, I figured 95% of it. The rest was simply tested with a vom and by process of elimination.

    parts I used
    • Honda 4th gen Accord Digital Climate Control
      Honda 4th gen Accord Evaporator temp switch grommet
      Acura 1st gen Cl blower transistor
      Acura 1st gen Cl hi speed fan relay
      Acura 1st gen Cl Outside air temp sensor
      Acura 1st gen Cl sunlight sensor
      Acura 1st gen Cl air mix motor
      Acura 1st gen Cl evap temperature sensor
      Acura 1st gen Cl aspirator union and rubber hose
      Acura 2nd gen TL aspirator and plastic hose
      Acura 1st gen Legend coolant temperature sensor
      Acura 1st gen TL heater valve and solenoid


    Wiring diagram I created


    Wiring connector pin out

    Since I was unsure of how everything would work out, I started out to get the basics that just required simple wiring working before removing the dash.

    Remove the console and dash bezel to get to the heater control out. I wanted to make a plug so I didn't have to cut the connectors off harness. I cut female side of an icu then soldered the dcc wires to it. Then I depinned the terminals of the stock male connector and inserted them into the ICU connector.

    Basic Power Wiring
    the basic power wiring is all present except for 12v constant power which can spliced into at the hazard switch above.

    Wire in the 12v, ign, gnd, a/c signal, illumnation and dimmer.
    dcc 12v wht/yel to hazard wht/grn
    dcc ign yel/blk to heater blk/yel
    dcc gnd blk to heater blk
    dcc a/c blu/yel to heater blu/red
    dcc ill red/blk to heater red/blk
    dcc dim red to heater red


    Test it out make sure it powers up, the backlighting works, and the compressor engages. Next wire the mode control motor and the recirculation motor. These are color to color with existing accord wires.

    Fresh/Recirc and Mode Wiring
    dcc grn/red to heater grn/red fresh
    dcc grn/wht to heater grn/wht recirculate
    dcc lt/grn/wht to heater lt/grn wht mode high
    dcc lt grn/blk to heater lt grn/blk mode hi/low
    dcc lt yel/grn to heater yel/grn modelow
    dcc blu/red to heater blu/red mode defrost/low
    dcc lt grn/red to lt grn/red mode common
    dcc blu to heater blu mode defrost


    After wiring, reconnect the original blower switch and turn on to get some air moving, test mode motor to make sure all is working. Test the fresh/recirculation motor. If all is well, move on to the blower transistor and high relay.

    Blower Transistor

    Remove the glove box, glove box bracket, and bolts holding right side of dash. Unbolt the ecu/tcu bracket and swing out of way. Remove two screws from bottom of blower to remove bottom lower trim. Remove clip to remove blower lower section. Remove the the 3 nuts and and unplug the wiring connectors then carefully remove blower motor.

    In order to wire the blower motor to the dcc, you need to replace the stock blower resistor with a transistor. The jdm cb7 mounts the transistor to the evaporator case. While this an optimum spot due to airflow, the USDM car evaporator does not have a spot where the transistor can mount so I just mounted it to where the resistor goes. You will also need to add a bypass relay to bypass the transisitor for when full output is selected. Any standard relay will work but I kept it factory and used a stock relay from a 1st gen Acura CL. Cut off the existing wires at the resistor and wire as shown below. This eliminates the need to run wires to the control unit and blower will unplug like normal.

    At transistor connector wiring
    blu/red transistor blower output blu/red blower reisitor connector
    org/blk transistor control blu/wht blower resistor connector
    blk transitor ground blu/blk blower resistor connector


    at high relay wiring
    blk/yel relay power blu blower resistor connector
    blu/org relay control blu/yel blower resistor connector
    blu/red relay output blu/red blower resistor connector
    blk relay input blu/blk blower resistor connector



    Blower transistor wiring


    After completing the wiring at the blower rewire the heater control blower speed connector as below.

    At heater panel wiring
    blu/red feedback blu/red at blower switch connecter
    blu/org hi relay blu/yel at blower switch connector
    wht/blu transistor control blu/wht at blower switch connector
    yel/blk relay power blu at blower switch connector


    At blower switch connector
    blk ground blu/blk at blower switch connector


    Blower switch wiring diagram

    The jdm dcc uses a transistor that looks similar to the g2 legend but that will not fit into the accord blower housing. The first gen legend does not fit and the 1st gen tl is not accessible enough to even try. The first gen CL transistor also does not fit but it can be modified to fit. The CL transistor and accord resistor mount differently. I cut down the larger transistor mounting base on a belt sander until it fit the opening. To install in the blower, I simply sandwiched the blower housing between the transistor heat sink and mounting base. I added a drop of thread locker just to be safe since removing the blower is a pain. I also bolted up the high speed bypass relay to the back of the blower.


    Comparison, accord resistor on left, CL transistor on right


    Comparison, CL transistor on left, accord resistor on right


    CL transistor separated


    CL transistor base plate ground down to fit blower housing


    Transistor heat sink in blower housing

    Air mix motor

    One the biggest hurdles to installing the digital climate control system is that the air mix on the standard accord controller is controlled by a cable. The DCC system use a motor to control the air mix. Since the all the cb7 DCC I have seen comes from RHD cars, none of the stock motor/linkage stuff bolts on the LHD heater box.

    I used an air mix motor from a 1st gen Acura CL. To mount close to factory jdm spot, all linkages need to be redone or modified plus a new pivot arm made. To make the install simpler, the motor can to be mounted so the output gear is directly centered over the air mix linkage center pivot. This is so it will have the same arc on the motor control arm as the air mix linkage arm. The location the motor needs to be mounted in, is where the floor vent outlet clips on the bottom of the heater housing.

    I made a bracket to bolt to the motor and to the bottom heater outlet. On the other side of the motor, I made a bracket from the motor to the metal 'L' tab that is used to clip the floor outlet vent on. I then had the three pieces welded together. Once the motor is perfectly centered, set the motor and air mix linkage to full hot. Loosen the motor arm's nut and align the arm with the air mix linkage control arm pin. Mark the motor's arm where a hole will need to be for the linkage arm pin. Drill a hole and slot it slightly so there will be no chance of binding. Use the plastic insulator so it moves freely.


    Heater box before


    Air mix motor and custom bracket


    Air mix installed with vent outlet cut out


    In action

    The air mix motor actually rotates the wrong direction. Hot is cool and cool is hot. The motor operates on reverse polarity output from the dcc so this easily fixed by swapping the two control wires. Now the hot/cool will be in sync but will go to full cool or full hot with nothing in between. What makes it operate in steps is feed back from a potentiometer in the air mix motor. The feed back is backwards when the motor wires are swapped for hot/cool direction. This is also fixed simply by swapping the 5v reference and sensor ground wires going into the pot.

    wiring
    pnk/blk to dcc pnk/blk
    gry to dcc grn/yel
    grn/yel to dcc gry
    red/wht to dcc red/yel
    red/yel to dcc red/wht
    Last edited by lucifer1; 09-30-2012, 01:37 AM.
    Manual Belt Conversion-Variable Intermittent Wipers-Steering Volume Controls-Rear Defroster Antenna-JDM Climate Control-MDX Steering Wheel-Lighted Mirror Switch-CL Trunk Solenoid-CL Homelink-Shaved Hood Squirters-Foglight Wiring Diagram-Door Panel Removal-Puddle Lights-Ambient Lighting-Door Speaker Install-Window Seal and Regulator Cleaning-Prelude Cluster-Mirror Tweeter Pods-Illuminated Window Switch -More Coming Soon

    #2
    Heater Valve

    The heater valve operates differently with the dcc setup. The normal setup varies the opening with air mix cable. The dcc leaves the valve open all the time and closes it when the temperature is set to max cool or 18c. It does this through a vacuum actuator connected to the heater valve instead of the normal cable. When max cool is selected, the solenoid is opened allowing vacuum to reach the actuator which closes the heater valve.

    While I think the stock accord cable setup will work fine with the dcc, I still went ahead and installed the vacuum setup as it was designed.

    The dcc heater valve uses a different arm for vacuum actuator. The keyway on both arms are same, the vacuum arm will bolt on in the same spot as the stock cable actuated valve. Unfortunately the heater valve itself needs the arm in a different spot to open and close properly with the vacuum actuator. So the accord cable heater valve has to be changed to the vacuum heater valve


    The heater valve arms cable on the left, vacuum on the right


    Heater valves fully closed. Accord cable heater valve on left, TL vacuum heater valve on right


    I placed the heater valve solenoid with the emissions solenoids. It really doesn't have any room the mount the solenoid but it will wedge in tightly after the casing is cut down. Remove the vacuum hose from one of the existing solenoids and connect to the vacuum 't' that came with the new solenoid. Connect the other two sides of the 't' to the new solenoid and
    existing solenoid. The heater valve solenoid output hose is routed to the bottom of the emissions casing and exits through a new hole I drilled.


    TL heater valve solenoid before trimming bracket


    Tl heater valve solenoid after trimming bracket


    #20 hose the needs to rerouted to 't' as source of vacuum for heater valve solenoid


    Heater valve solenoid wedged in


    Vacuum 't'd in


    new vacuum hose from 't'


    Heater vacuum actuator hose running out the bottom

    wiring
    Cut the black vinyl tubing so that there is just enough left to cover the wires on outside of emissions casing. Cutting the vinyl also makes it easier to run new wire through to the 4 pin connector.

    Wire the blk/yel solenoid wire to existing blk/yel power wire.
    wire the yellow solenoid wire to dcc pnk/grn

    Run yellow through the vinyl tubing and into the open terminal spot of the 4 pin emissions connector. Then add a pin into the other side of the connector and run wire to the dcc. Use the fog light wiring grommet below to route wire inside. Add a 3 pin connector to unplug for servicing.


    Empty terminal slot on 4 pin connector.


    Filled terminal

    With the emissions box still removed, remove the fuel filter bolts and charcoal canister to access heater valve. Remove the heater valve and replace it with one from the vacuum actuated heater valve. Cut the TL bracket down and mount together with stock accord bracket by heater valve screws. I welded the two brackets together with a reinforcement plate for extra support. Run the vacuum hose to the solenoid.


    Tl bracket bolted on accord bracket before cutting


    Tl bracket and accord bracket welded together and reinforced


    TL heater valve installed

    That completes the basic setup and you should have working fully working heater and a/c. If you want to make the auto climate control work, the rest of the sensors(sunlight, evap temp, outside temp, interior temp aspirator, coolant temp, and vss) need to be installed.

    Evaporator Temperature Sensor
    Any evaporator temperature sensor from a Honda climate control system will work. Electronically they are all the same. I used one from a 1st gen Acura CL. The evaporator temp sensor goes into the evap housing on the heater side. The CL sensor has a clip on it that mounts into the fins, fifth row in. My a/c was already discharged so I removed the evaporator to make it easier work on. It was actually pretty dirty inside and couldn't be cleaned properly without removing it. The evaporator has a temperature switch in it already that is not used on the dcc system. Unplug the temp switch and connect the wires together to so the a/c signal will pass on. I just left it alone as another safety.I drilled a hole on top the housing near where the original temperature switch enters. I used a temperature switch grommet to pass the sensor through and seal the hole. I also drilled a hole in the housing tab to clip the connector on.

    wiring at evap temp sensor
    brn to dcc brn
    yel/grn to dcc yel/grn



    Wiring passing through new hole and accord grommet, connector mounted to housing


    Evap sensor clipped in to evap core

    Outside Temperature Sensor

    The JDM CB7 outside temperature sensor clips on to the bumper. This style of sensor can be found on the 1st and 2nd gen Legends but any outside temperature sensor from a Honda climate control system will work. Electronically they are all the same. I used one from a 1st gen Acura CL with the plastic casing and an actual bolt down mounting bracket.

    The outside temperature sensor mounts on the core support behind the bumper grill opening. I actually mounted it towards the passenger side of the bumper opening to a power steering cooler bracket bolt. Run both wires back to the dcc. Follow the same path as the fog light wiring harness and through the 3 pin connector from the heater valve wire.


    Outside temperature sensor installed

    wiring
    brn/wht to dcc brn/wht signal
    yel/grn to dcc yel grn sensor ground


    Sunlight Sensor

    Any sunlight sensor from a Honda climate control system will work. Electronically they are all the same. The sunlight sensor goes on top of the dash either in the center or off to the side. I used one from a 1st gen Acura CL/6th gen Accord since it would mount the best. Make a hole in the dash between defroster vents and clip it in. This will take a bit of time since the dash is metal between all the foam.


    Sunlight sensor installed


    Sunlight sensor from back of dash

    wiring
    wht/red to dcc wht/red signal
    yel/grn to dcc yel/grn sensor ground


    Coolant Temperature Sensor

    The coolant temperature sensor for these older systems is actually in the heater housing and does not use the signal from the engine like newer ones. The sensor mounts against the heater core inlet side. This requires removing the heater housing to get to the heater core. I used a sensor from a 2nd gen legend. 1st gen legend will also work and is much harder to remove out of donor vehicle.


    1st and 2nd gen Legend coolant temp sensor

    The sensor will fit under the heater core cover but the cover still needs to be trimmed to fit back on a bit better.

    wiring
    pnk to dcc pnk signal
    yel/grn to dcc yel/grn sensor ground




    Before coolant temp sensor


    Coolant temp sensor installed

    Interior Air Temperature Sensor

    The interior air temperature sensor is built into the bottom right corner of the controller but still needs air drawn through it to work accurately. The accord uses a small fan mounted on the outside of the heater box connected by a hose to the controller to draw the air. The fan is wired directly to ignition power. An identical fan can be found mounted directly on the gen2 legend climate control unit


    2nd gen legend fan

    On newer models the sensor connects through a tube to a nozzle(aspirator)mounted to the heater housing, the air exiting through the aspirator draws air through the tube. There seems to be different versions of aspirators in every generation. 1st gen CL and 6th gen accords aspirator mount on a male protrusion the heater housing. The 2nd gen TL has the male part in the aspirator and just a plain hole in the heater housing.

    I chose to use an aspirator from 2nd gen Acura TL . It needs to mounted in a spot where air is constantly flowing and not closed off by any of the diverters. Meaning after heat/cool blend doors but before the hi/low/defrost diverters. I decided to mount it in the front corner on the drivers side. The aspirator uses a corrugated flexible plastic hose to the sensor or a tube union. This hose not long enough or sized to fit the dcc. I used a tube union from a 1st gen Acura CL. From the tube union to the dcc, I used the matching rubber hose from a 1st gen Acura CL.

    Cut out the odd shape of the aspirator inlet in the heater housing. Use a screw to secure it. Route the matching corrigated hose from the side of the heater box and secure the tube union. Run the ruber hose from the union to the dcc.


    Heater box before aspirator


    Aspirator hole cut out


    Aspirator mounted

    Attach the clear flex tube and union to the aspirator. Drill a hole in the heater housing for the tube union locator pin. Then secure the tube union wth screw. Attach generic rubber hose to the other end of the tube union and route towards passenger side. Cut a small 90 degree piece off the molded rubber hose and attach to the dcc. Connect the generic hose and factory hose together. I used aluminum tube and flared it on one side since hoses are different sizes.


    aspirator hose


    pieces for the dcc


    connected

    Speed Sensor
    Finally connect the vss wire to cluster. Since the dash is out I ran it to the cluster to keep the wiring inside the dash.

    dcc org to cluster org bottom left connector



    Now put everything back together and enjoy unless you want to be ultra cool like me and add steering wheel controls to your dcc



    Steering Wheel Control of DCC
    Remove the dcc and disassemble. Solder wires to the back of switches for temp up, temp down, fan, mode, auto, and off. Run the wires to a relay for each switch to be used. The buttons on the steering wheel will trigger the relays which will act like pressing a button on the dcc. I used small reed relays so I could fit them inside the dcc unit.





    I modified the switches of my 2009+ Tl steering wheel so instead of 3 switches on 1 wire, I have 3 discreet output wires.





    Last edited by lucifer1; 09-30-2012, 01:36 AM.
    Manual Belt Conversion-Variable Intermittent Wipers-Steering Volume Controls-Rear Defroster Antenna-JDM Climate Control-MDX Steering Wheel-Lighted Mirror Switch-CL Trunk Solenoid-CL Homelink-Shaved Hood Squirters-Foglight Wiring Diagram-Door Panel Removal-Puddle Lights-Ambient Lighting-Door Speaker Install-Window Seal and Regulator Cleaning-Prelude Cluster-Mirror Tweeter Pods-Illuminated Window Switch -More Coming Soon

    Comment


      #4
      Are you for real right now? This is some legit work man.
      '93 H22A 5SPD SE - MRT - DIY-Turbo Sizing - Chassis Dynamics Data

      Comment


        #5
        Great job. And thank you for taking the time to make this very informed diy.
        "My FOR SALE thread - Click here"

        MEMBERS RIDE

        99 SILVERADO

        WHEEL FLIP

        Comment


          #6
          This is madness!!!!!


          Very well done, (still one of the hardest mods out there for the CB)....You have video as a proof that actually works and your DIY very well detailed.....


          It's good to see knowledgeable people willing to share, You took your time doing this DYI, taking pics, and remembering every single detail....


          Well done once again Lucifer.... is that your actual nickname or something? LOL
          JDM Parts for sale

          Comment


            #7
            Amazing work. Most of us are in awe of what your capabilities are when it comes to figuring out difficult projects. Thank you for taking as much time as I know even just this post took to contribute to this site. For those of us that have actually analyzed the issues presented by this install and the components theoretically required, we know exactly how difficult this was to come up with all of the information and assemble different parts to try them out. Not many people here will truly understand what you have invested in this and will still hope to order some parts and do it in a weekend. Bravo, good sir. Bravo.

            One question, though. You mentioned that the older style units did not measure an engine temperature at an existings coolant temperature sensor, but inside the cabin. Why can't you simply obtain your signal from the sensor on the engine or a fan switch anyway? Would it be hotter at those points and outside of any parameters that the DCC would know how to handle? What's the reason?
            My Members' Ride Thread - It's a marathon build, not a sprint. But keep me honest on the update frequency!

            Comment


              #8
              Why does the system use a light sensor?
              Can you turn off those beeps?



              Nice write up btw.

              Comment


                #9
                Originally posted by Jarrett View Post
                Amazing work. Most of us are in awe of what your capabilities are when it comes to figuring out difficult projects. Thank you for taking as much time as I know even just this post took to contribute to this site. For those of us that have actually analyzed the issues presented by this install and the components theoretically required, we know exactly how difficult this was to come up with all of the information and assemble different parts to try them out. Not many people here will truly understand what you have invested in this and will still hope to order some parts and do it in a weekend. Bravo, good sir. Bravo.

                One question, though. You mentioned that the older style units did not measure an engine temperature at an existings coolant temperature sensor, but inside the cabin. Why can't you simply obtain your signal from the sensor on the engine or a fan switch anyway? Would it be hotter at those points and outside of any parameters that the DCC would know how to handle? What's the reason?
                Ptetty much, I thought about using an engine sensor but figured the temps would be different and the dcc was designed around a specific spot. That coolant sensor is also used by Range Rover in late model vehicles.
                Manual Belt Conversion-Variable Intermittent Wipers-Steering Volume Controls-Rear Defroster Antenna-JDM Climate Control-MDX Steering Wheel-Lighted Mirror Switch-CL Trunk Solenoid-CL Homelink-Shaved Hood Squirters-Foglight Wiring Diagram-Door Panel Removal-Puddle Lights-Ambient Lighting-Door Speaker Install-Window Seal and Regulator Cleaning-Prelude Cluster-Mirror Tweeter Pods-Illuminated Window Switch -More Coming Soon

                Comment


                  #10
                  Originally posted by ChIoVnIdCa View Post
                  Why does the system use a light sensor?
                  Can you turn off those beeps?



                  Nice write up btw.
                  I would think to better calculate air temp and fan speed. Higher fan speed with more sunlight to cool faster.

                  I don't know how to turn off beeps, but you could remove the beeper from inside.
                  Manual Belt Conversion-Variable Intermittent Wipers-Steering Volume Controls-Rear Defroster Antenna-JDM Climate Control-MDX Steering Wheel-Lighted Mirror Switch-CL Trunk Solenoid-CL Homelink-Shaved Hood Squirters-Foglight Wiring Diagram-Door Panel Removal-Puddle Lights-Ambient Lighting-Door Speaker Install-Window Seal and Regulator Cleaning-Prelude Cluster-Mirror Tweeter Pods-Illuminated Window Switch -More Coming Soon

                  Comment


                    #11
                    You. Are. Amazing. Thank you so much for all you've done for the CB7 Community!!!
                    blackROSE Member, with a focus on VIP Style

                    Comment


                      #12
                      Simply amazing work!

                      I was considering using a ton of custom electronics but it looks like you got it all mapped out with OEM parts. Great job!

                      Comment


                        #13
                        Good work man. This is a lot of work and dedication. Hopefully someone will follow this and do it. I might someday.
                        10th Anniversary Accord.
                        05 Audi A4 Ultra Sport 6MT.

                        Comment


                          #14
                          Wow very intense and detailed work!

                          Reminds me to try to do something. Cpmike and I have been having so many extra parts but never attempted!

                          Thanks!

                          Comment


                            #15
                            Awesome writeup. Thank you!

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