My DeVille has a slow drain on the battery and i cant figure out from where. i tried putting a test light on between the battery and the cable and then pull fuses until the light went out but still didn't find it. also my climate control wont go into auto, it just stays on econ. anybody have any ideas? :hmm:

I have a similar problem. I have traced it to the body 3 circuit. I see by the schematics that there are 2 relays in this circuit. I am wondering where these would be located, so I could take a chance that these are the problems. In the meantime, I put a cutout switch between the battery and the cable so if I am not going to drive it for a while, I can cut the power, otherwise the battery will be dead in 3-4 days.

http://www.cadillacforums.com/forums/electrical-technical-information/134509-dreaded-dtc-c1739.html
This should help you narrow it down, so you'll know which circuit it's on. Use a DVOM instead; a test light draws too much current, and won't dim enough to allow you to see the voltage drop once you disable the circuit causing the draw. You want to start with the battery fully charged (preferably with a battery charger.) This way you won't have to wait to see if you've solved your problem...
As for the A/C, pull the fault codes; it's likely either "refrigerant low" or "low refrigerant pressure". If so, you'll then need a licensed A/C shop of course. If you've had it serviced recently, take it back and ask them to check/replace the pressure sensors. When these fail they can cause an otherwise fully charged system to malfunction. These switches are used because the refrigerant also carries the compressor oil through the system, and any drop in pressure or loss of refrigerant will eventually cause the compressor to fail.