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Question:

How to fix Ac in 91 Cadillac DeVille?

The service air conditioner light on our 1991 Cadillac sedan deville 4.9 comes on when I turn the air conditioner on. The electronic climate control will not let me turn on the heat or the ac. It just defaults to economy. The ac at this point no longer blows cold air. I push the off button and eventually the light goes out. Do you have any thoughts on what may be causing this? Thank you for your help in advance. Sincerely.Also I don‘t know if this matters but I had someone look at it and it was overcharged and I have never charged it and Ive owned it since new and it always worked like a charm

Answer:

Those auto climate control systems are often a real pain to properly diagnose and repair.and costly. To start with, you should check any fuses for the system to see if they are blown and have the a/c system checked for proper chargeundercharge or overcharge can cause the system to stop working. The main PCM computer is also involved in operating the HVAC system depending on engine load and throttle position, engine temp, etcso you should have it tested for trouble codes.local parts stores usually offer this as a free service. Any trouble codes might lead to better diagnosing. A shop would have to test to see which system sensors, relays or other areas are not getting power or malfunctioning or diagnose a problem with the main climate control unit. Parts and labor can get pretty spendy so many people opt to switch out the automatic climate controls for a manual control system if the car is worth keeping long term or alter the climate system to perform more manually.bypassing the computer controls with on-off switches mounted to the instrument panel or console mounting platform.

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