Need some advice on where to look to get my climate control working again on my '96 C-4. A couple of weeks ago the green light above the AUTO button would blink for a while after I started the car. The owner's manual says that it does that when there is a possible electrical problem. Two weeks before this happened, the battery died, so I had the dealer install and pro-rate for a new one. The week after that, the service engine light came on and I had to replace the O2 sensor on the right side.

THAT is when the AC quit working. All I can get it to do is blow hot air for a while and then it will blow outside air. I don't hear the compressor cycling and the cooling fans do not kick on. I can get the inside fan to work if I use the manual control.

Is there any link to the new battery or the O2 sensor? Are there any circuit breakers or fuses I should check ?

I costs $90 just to drive it in the shop, and I don't want to be charged that much for something simple that I could take care of.

Any suggestion?

 

Pull the trim panel around the control off, like you want to take it out. the face on the control is held on by two clips. 1 on each side. take them off carefully and remove the face.There is a circuit board in there that plugs into the back of the face. Clean the contacts and re-install the face making sure the board plugs all the way in. Hope this helps you. Good luck.
Bryan

 

Before you do anything, first run the built in diagnostics.

To do this, push and hold the fan up and down arrows at the same time for about 5-6 seconds. The LCD will show "-00". Push "Auto" and the LCD will show any fault codes that are stored.

While in the diagnostic mode, it is possible to show a number of other system parameters also, but the one you want is "-00".

Fault Codes

00 Not used
01 Temp. Door Motor Circuit Fault
02 Temp. Door Motor Circuit Fault
03 Ambient Sensor Open
04 Ambient Sensor Short
05 In-Car Temp Sensor Open
06 In-Car Temp Sensor Short
07 Solar Load Sensor Open
08 Solar Load Sensor Short
09 Low Freon Detected
10 UART Failure

If you don't show any codes then the most likely problem is dirty contacts on the push buttons. Instructions:

http://forums.corvetteforum.com/show....php?t=1519199

For an excelent review of the C-68 Controller:

http://www.batee.com/corvette/acrepa...oard/c68.shtml

 

wow you late C4 guys have it made with dianostics!

My 89's AC controls blink like a broken carnival sign unless i tap it hard a few times to make it stop.

 

All right! Thank's for the great advice. I got a 00 diagostic code, so this weekend I'll clean the contacts per the very good instructions.

Thank's again

 

The '89 has limited built in diagnostics too with a system problem indicated by a flashing LED above the Exterior Temp Readout. Access by holding the Exterior Temp Button while pressing and releasing the Auto button. A mode number will display - advance it by pressing the Warm button until you see 08. Press Cool for Codes. 00 is no faults; 01 is an open in the Temp Door Motor feedback circuit; 02 is an open in the Outside Air Temp Sensor; 04 is a short in the Outside Temp Sensor; 08 is an open in the Inside Temp Sensor; 16 is a short in the Inside Temp Sensor.

None of these parts fail on a regular basis, so codes are rare - in fact I don't think I've ever seen a HVAC code posted around here (for the '89or below).

Flashing Panel lights can be a power or ground problem. Memory is from the Courtesy Clock Fuse - if it won't retain temp settings after it's shut off, suspect this circuit or the ground. Ground runs to the left kick well. Remove the hush panel to access. There are 2 there - same circuit in the Manual, but the HVAC runs by it's lonesome to this lug. Ignition Power is from the Gages Fuse - lot's of other things share that circuit, so if it was the fault, there would probably be other problems. If power and ground are good, you need a rebuilt panel (or if you know your way around a circuit board - I don't - some have taken them apart and resoldered with good results).