Anyone with dual-climate controls read this. Kinda long.

[dragon459]

I recently had some problems with my AC and found an old message board reply that helped me alot. I willl post it so maybe it will help others

 

Original post:

 

 

tzampini@aol.com (TZampini) wrote:

>Hi all,

>

>I have a 91 Buick Park Avenue with the dual zone climate control. The

>system

>is way out of wack. The other day I had the temp. set to 70. Everything

>seemed

>to be OK until after driving the car for about 20 minutes. Then, there was

>cold

>air coming from the driver's side, and hot air from the passenger's side.

>The passenger had his dual control set to neutral. I tried shutting off

>the dual

>and run straight AC, and the problem was still there. Then I shut off the

>AC

>and pressed the ECON (economy/vent) button. The problem was STILL there.

>

>Can someone explain to me how this system works? Are there sensors that

>measure the indoor temp? Are the baffles vacuum controlled or electrically

>controlled? What is the best source of information to help me solve this

>problem?

>

>Thank you for your help,

>

>Tony Zampini

>TZampini@aol.com

 

The temperature doors are controled with electric motors. Several different

things could be causing the motors to do what they are doing. Disconnect the

battery, wait a few seconds then reconnect. The motors should go through a

"recalibration" procedure where they are driven to both ends, the full hot

and full cold sides. This takes about 2 minutes. If you want to watch the

motors do this, remove the glove box and lower hush panel on the passenger side.

The motors are inside a black plastic box mounted on the heater/evap case.

This plastic box is the HVAC computer. The upper motor is the passenger side

and lower is the driver's. Motor linkage comes out of the box and connects to the

temperature doors. If the motors do not move, or they move and you still have

the same problem try this procedure: Hold down the OFF and WARMER keys on the

control head at the same time for about 5 seconds. The display will go blank,

let go of the keys. Error codes for the HVAC system will then be displayed, a

different error code every second. If no error codes exist a "00" will be

displayed. Don't worry about a "52" if it shows up, the battery reset will cause

that one. A "40" is bad driver motor (lower), "41" is bad passenger motor (upper).

Other error codes to note are "10" outside temp sensor, "13" incar temp sensor,

"15" driver solar sensor, "17" passenger solar sensor, "35" loss of communication

with control head, "38" loss of vehicle data communication (vehicle wide data bus).

It sounds like whatever you find, the HVAC computer will need to be replaced.

More than likely a motor is bad or the microprocessor output that drives the motor

has failed.

Replacing the HVAC computer is relatively easy. Disconnect the motor linkages, they

snap right off, and the wiring harness. Remove the vacuum lines from the front with

a deep socket driver, a single nut in the middle holds it on. Then remove two 7mm

screws, one is in the front-middle and the other is near the lower motor. The box

then slides out forward. You'll have to fight the lower part of the dash to get it

out but with some work it will fit.

When putting in the new one, just do the above in reverse. Before connecting the

motor linkages start the car and let the motors run through their calibration

procedure, then set the temperature to 90 deg F. on the control head. Watch the

motors move until they stop, then pull the door linkages over until the door is snug

against it's stop and snap the linkage in to the motor arm. This is important so

the system will control the temperature in the car correctly.

If you have questions or any problems email me. Good Luck!

 

--

Chris M. Puranen, N9BJX cmpurane@mail.delcoelect.com

 

Delco Electronics Corporation

Air Control Systems

[Baddflash]

Don't own one but still good info to know.