Cadillac Repair: 1998 Cadillac Seville Air conditioning problem, automatic door locks, 1998 cadillac seville

Question
My father in law has a 98 Cadillac Seville.  The compressor stopped working at the same time the gas door stopped opening, the trunk wouldn't open, the gas gauge quit working, the automatic door locks quit working, the cigarette lighter quit working.  The gas cap, the trunk, the automatic door locks and the gas gauge started working after replacing a blown fuse, but the cigarette lighter and the air conditioner still do not work.  I can't find another blown fuse.  The air conditioner has no power to the compressor clutch.  I swapped relays to see if a relay was bad.  The horn works, the lights work, everything else works except the air conditioner and the cigarette lighter.  I get 12 volts to the low pressure switch at the dryer.  I was unable to determine if I was getting voltage to the switch on the suction line at the compressor due to the engine being hot.  My volt meter showed about 3 1/2 volts to the 2 switches on the high pressure line. What else can I try?  What voltage should be read on the 4 switches in the system?

Answer
Hi Paul, the compressor clutch gets its power from a fuse and relay that are located in the under hood junction block. With the relay out make sure there is power on 2 terminals with the engine running, 1 with is a switched ground that the PCM turns on and off and the last wire goes to the compressor. With a fused jumper wire you could jumper the battery wire to the comp. wire and the comp. should be heard to engage. If not then check the wires to the compressor clutch. There is an A/C CLU 15A fuse in the junction block that feeds the relay. If you don't get the switched ground then the PCM or wireing could be bad or a troubecode has been set and needs to get fixed and code cleared. The sensors have 5 volts going to them and depending on the resitance of the sensor the voltage out will be lower. The power to the cig fuse should be in the same underhood junction area. Otherwise they also put fuses under the rear seat and will need to get a wireing diagram to trace the circuits and fuse locations. Bill