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Old 09-30-2012, 12:30 AM   #2
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Join Date: Feb 2007
Location: Ca
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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

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

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

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.

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


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 at 12:36 AM.
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