I recently purchased my first US made car since my ’69 Tempest (a ’97 SLS) that I believed was in mint shape (fully loaded) – and all-in-all it is. At 76,000 miles I had to replace the Northstar (over heating etc and heads and gaskets not in great shape) so I’ll take that one as a lesson learned. But since then I’ve had nothing but problems with the electrical (I believe). The A/C has been my biggest problem child and that “other Cadillac” forum – full of sarcasm and criticism, was of no use.
Initially there were no DTC to indicate any problems with the A/C – no low coolant or compressor in the ACM. I do know that the BCM may be defective (see DTC below) but somewhat sure that isn’t the issue with the A/C.
When a friend (A/C peep with the right tools and 80 lbs of 134a) put the gauges on the LOW side and it pegged the gauge and freaked us both out. The line was highly charged and he decided to bring it back down to 30 psi. Since then the A/C Low coolant and Compressor Errors are showing up and the compressor is still not engaged (forgot to mention that before) – Plus I now have Engine Idle Error Service Fault.

I would really like to believe this is not as bad as it seems but the excessive pressure on the LOW side is back up again (over 45 psi). I don’t expect to fix it under the tree although I would love to try (still pretty handy) but I may need an A/C pro (not friend) to flush, vacuum, and check the compressor with 12 volts before paying the bottom feeders the $1500 they want for a $375 compressor + labor.

Current DTCs:
PCM P0550 POWER STEERING PRESSURE SWITCH CIRCUIT
P1654 (HISTORY) CURSE CONTROL INHIBIT OUTPUT CIRCUIT
IPC B1552 (HISTORY) KEEP ALIVE MEMORY ERROR
B1348 (HISTORY VERLY LOW AC REFIGERANT
TCS C1255 (HISTORY) EBCM INTERNAL MALFUNCTION
PZM B1552 (HISTORY) KEEP ALIVE MEMORY ERROR
B1558 (HISTORY) BCM EPROM CHECKSUM ERROR
B2502 (HISTORY) AUTO TRANSMISSION SHIFT LOCK CONTROL SHORTED TO GROUND
ACM B1348 VERY LOW A/C REFRIGERANT PRESSURE

I love the car, the ride and the looks and I can afford the normal stuff but… another $1500 after a $7000 long block replacement?
Any ideas… Did I leave anything out?
Frustrated and hot in Florida…