Compressor not working - where to start?

[itzed]

'95. I want to look for the obvious before I take it to the $tealer. I'm not sure if the refridgerant is low or not at this point. I already tried jumping the two wires that lead to the compressor and that will not kick it on. This winter I replaced the radiator, waterpump, hoses, and thermostat, and afterwards when testing I could not get the radiator fan to come on. Of course it was 20 degrees outside and it never really got hot enough to come on. Even now, the thermostat opens and closes and the coolant will flow but the temperature guage only moves slightly when that happens and always shows in the normal range. Is there something simple I can check that might prove or disprove these things are related? Somehow I feel they might be. I'm OK with mechanical repairs but I'm not that experienced with electronic or AC systems.

Ed

[itzed]

bump. Anybody?

[Manny_boy]

Jumping your compressor leads might not do it, because it has to create an elctromagnetic field to close the clutch plate. A better test would be to find the AC relay, and place a jumper between terminals 30 and 87. That will tell you if your compressor is operating.

Second, there is a low pressure switch located on or near your accumulator, if your pressure is low, your compressor will not engage when you turn your A/C on if the switch is operating properly. I believe the switch has three leads. One is ground, one is a 5v signal reference for your ECM, the other tells your ecm whether or not your pressure is sufficient (IIRC).

as far as your fans - I'm assuming that you have 2 - one of the fans only comes on when either: you engage the A/C, or you reach the upper threshold of the temp range (and at that point, the first fan should have been running)

You mentioned that you changed your thermostat, radiator and hoses. Make sure you bleed all of the air out of your system. Air pockets seems to play havoc with our cars as far as operating temps.

Also there is a temperature sensor screwed into or near the rear head. This is the sensor that the ECM relys on for coolant temp. There is also a separate, single wire temp sensor that is used for what the gauge reads. If your temp sensor is bad, it could give the ECM false readings, that could cause problems. (That usually causes other drivability symptoms though, has your car been running rich?)

[itzed]

Thanks for the reply. The car has been running fine, almost too good for a car with 246K on it. I'll try jumping the relay and see if that gets the compressor running.