92 A/C (no clutch engagement)

[MERC_DoD]

When I bought the car there was a sticker under hood that says it was retrofitted to R-134a. A/c has always worked fine. A few days ago I noticed a noise that sounded like the tab that scrapes the rotor when the brake pads get low, I think the sound was coming from the compressor and I noticed that the a/c did not work any more. After trying it several times it started working again and I did not have the noise anymore but the a/c stopped working again. I hooked up a cheap guage and it showed "GOOD" for refrigerant. I think that was the last time the compressor clutch came on. The fuse in fuse box is good. Not sure what I should do next. I think I will unplug the compressor, insert 12 volt tester, turn key on and see if I get any juice. Does car have to be running or key in on position good enough? Any help or suggestions would be appreciated in troubleshooting this issue.

[rayp40]

The real pressure test is when the A/C is running. The compressor causes the pressure to drop on the suction side which is probably where you tested. There is a low pressure cutoff switch in the system and if the refrigerant pressure is too low, the compressor won't run. That's the number 1 cause of the problem. The switch should be on the suction line right near where it connects to the compressor. There are two wires on it, and you can pull the connector off the switch and short them together and see if the compressor runs. If it does, you need another can of R-134 in your system.

Leaks are a fact of life with car A/C systems because the shaft seals on the compressors aren't 100% effective. We have 4 cars in the family and I buy R-134 by the case. Every spring I usually have to put 1 or 2 cans in all our vehicles.

Good luck.

[brcidd]

'92 bonnys were known for intermittent a/c relays-- next time it should be on and it isn't- tap on the relay--- should be first or second on left (as looking at relay rack) under the plastic cover......on firewall next to accumulator...