Mailbag: 1995 Cadillac STS A/C won't kick on

[Bruce Nunnally]

Received this question on the blog:

95 Seville STS, had AC Compressor rebuilt, new drier, orifice tube, installed on my own, had system evacuated and charged. Holds freon, no leaks. AC won’t kick on unless you short the the relay. Any advice what to do to have the system turn on from cabin control control module?

[Cadillac Jim]

Clear the OBD codes and try again. The simplest way to do this is through the A/C controls but you can do it by simply disconnecting the negative terminal of the battery for 30 seconds, then putting it back.

[rockfangd]

I completely agree with above. System will not function with a code present.

If that does not resolve it check the wiring to the pressure switches by the cowl and make sure they are plugged in and not damaged.

How much freon did you charge?

[Cadillac Jim]

Clearing the codes, turning on the A/C and experiencing the malfunction if it continues, then running the codes again before turning off the key should reveal the culprit through a CURRENT code.