1986 Cadillac Seville V8 Front Wheel Drive Automatic 53000 miles
Question: 2004 Sedan Deville AC. I saw your posts on the internet and you guys really know your stuff! Up to now, it has been difficult getting truly professional advice on this topic (even at the Cadillac garage), so I was wondering if you could respond to what is probably a very basic question for you: PROBLEM: My Cadillac (88,800 mostly highway miles) now shows the amber " Service AC" light for several seconds after starting [not just bulb check, but also may not be 29 sec. As per owner's manual p.128]. The climate control is now always defaulted to the ECON mode. If I push the AUTO button, the light comes back on & it goes back to ECON mode.
SERVICES PERFORMED: I have always kept the AC system serviced, & @ 123k & 127k have had the AC system checked with dye, black light and " sniffer leak detector.&Quot; It showed " seeping at the compressor and evaporator.&Quot; Car has been carefully maintained since brand new (father owned up to 40k miles); although I note that at 30.5k miles the evaporator core was " blown" & replaced (surprising) by the Cadillac garage. In the nearly 100k miles since then, I've done nothing to AC other than had it checked, periodically recharged & had the compressor relay replaced (31k & 120k).
Answer: If the amount of refrigerant in the system is correct, then we suspect the fan controller module is malfunctioning.
Is the refrigerant amount correct? If so, I would suspect a pressure sensor, or restriction possibly. The fan controller would not cause this concern. It is defaulting to econ to prevent compressor damage. We need to know that it has the correct charge before you can go any further.