1990 C4 Climate Control Problems
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3rd Gear
Joined: Jun 2017
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1990 C4 Climate Control Problems
My 1990 C4 manual trans I recently bought has some strange ECC problems. The display works, but green lights flash indicating trouble codes. When driving, the AC will work, but then turn to heat. The outside temp reading on AUTO is wrong, but when I select the feet only selector the outside temp is accurate. When checking the error codes on the control, I get 02, 04, 06 and I think once it displayed a 10 (but didn't recently). Thinking it was the Programmer module, I painstakingly removed it in order to check the circuit boards thinking that was my issue. All seemed fine (relay coils measures around 83 ohms, capacitors measured fine, diodes were good). At my wits end, I checked all of the vacuum lines in the engine compartment and under the dash. All good as far as I could tell. Has anyone encountered similar problems? What was your fix? I have been all over YouTube and Google, and have not come up with my exact problem. (by the way, all was done with battery disconnected). I have the dash half torn apart, and would like to recify this soon. Thanks!
