ok, i live in columbia sc and when the a/c goes out in the middle of august it's a BIG problem.this is a VERY late 1994 with the r134 system it shows a full charge when off but the compressor wont kick on when the a/c button on the dash is pushed. i borrowed a few a/c relays from a friends wrecked saturn to see if maybe the relay was the problem. it wasnt. the light on the dash comes on when i hit the button, just no cold air, no sign at all that the compressor is coming on. there was never ANY indicator that there was a problem. one day it worked, the next day it didnt. all fuses seem to be ok as well. the car is an auto trans, non abs if that matters. it's also a LATE 94 and has the system that uses r134

 

what are high and low side pressure readings? Sounds like A/C clutch not kicking in may be indicative of compressor clutch failure. Be aware that there is a thermal cutoff "switch" wired into the compressor unit itself -- if this burns up, compressor won't turn on. Also be aware that there is a low pressure switch in the low side line over by the underhood junction block. If system pressure is too low (true refrigerant pressure), this switch will open and inhibit the voltage from from reaching the A/C clutch.

 

can i run a jumper to the a/c clutch without damage to see if the clutch is ok ?

 

yes indeedy -- this would be the next troubleshooting step following fuse and relay confirmation.

 

that worked, the compressor kicked on when a jumper was used.

 

ok -- so the A/C request signal is probably getting to the PCM, but the A/C relay is being inhibited from engaging. This is most likely due to a low refrigerant condition though there may be other causes.

We really need the high side and low side A/C pressures to figure out what's up.

You can get a usable set at autozone or similar for under $60......