A/c compressor

[79 GP 4 speed]

How can I tell if my a/c compressor is bad or is it not turning on due to low freon? Any help is appreciated and thank you in advance.

 

[Texas82GP]

Is the car still an R12 system or has it been retrofitted to R134-A?

 

[79 GP 4 speed]

It's still r12. I'm not sure if the clutch isn't engaging do to low freon or if it's froze. I saw a conversion kit online that doesn't require you to evacuate the system, I just don't want to buy it and then find out I need a compressor.

 

[Texas82GP]

Do you have access to a gauge set?

 

[79 GP 4 speed]

I will check with a few people I know

 

[Texas82GP]

Best approach would be to see if it has a charge with a gauge set. You can hot wire it to run. With the engine idling, turn the A/C on. Remove the plug at the low pressure switch on the accumulator and jump across it with a paper clip. Put your hand on the accumulator where it attaches to the evaporator. If the compressor clutch engages and the evaporator gets cold, the system is working but may need additional chage depending on the pressures. Don't let it run long if it doesn't get cold. Don't run it at all if you put gages on it and the system is flat. Follow up and we can take it from there.

 

[79 GP 4 speed]

I will try that if I can't get a gauge set

 

[Texas82GP]

Another easy thing to check is to pull the plug from the low pressure switch on the accumulator. With the key on and the A/C on, check for 12V in that plug with a test light or a volt meter. You should have it at the light green wire. If you are getting 12V at the low pressure switch and the clutch won't engage, then either the system is low on charge, you have a bad or stuck low pressure switch, there's a problem in the wiring to the clutch, or there's a problem with the clutch.

 

[79 GP 4 speed]

Should I be able to turn the compressor by hand?