AC clutch not engaging, need more help
 

2000 Jimmy. No AC, AC clutch doesn't engage. I figured just low on R134 since it had to be recharged last year also. (I did have the compressor replaced a few years ago, not original equipment.) I have a friend who is going to work on it who has all the proper equipment to do it correctly, but little free time. So I was going to do a quick DIY recharge to hold me over before I die of heat exhaustion. I wanted to test what was suggested here on other posts before wasting the gas. But so far no luck.

Did these tests with car running, AC on max. I jumped the low pressure switch harness connector and clutch still did not engage. Checked fuse in the engine compartment fuse box, and swapped out relay with another that was the same. Both good (swapped horn relay and horn honked). Unplugged the power connector (right behind clutch on top of compressor) and tested the connector. Reading was .01-.02, tested with low pressure connector jumped and not jumped. Doesn't seem right but I saw someone else posted the same voltage and nobody ever said much about it.

What next? I believe the plug on back of compressor is the high pressure switch. Should I test that also, even if the system pressure is most likely low, can this switch go bad and shut everything down? Do I jump the connector same as the low pressure side, at the harness connector, not the switch? Can something inside the compressor just be fubar? Are there any other fuses that I missed? What about the voltage at connector, why so low? I've read about jumping the relay socket, should I try that and what does it prove?

Any help would be appreciated. Seems everyone else's problems were fixed by simply recharging...

My clutch was rusted up and a couple of smacks with a hammer got it going, Sprayed it with WD40 and all has been well since.

A quick way to check the clutch is to run +12V from the battery directly to the clutch. If it kicks on the problem is elsewhere. If it does not than you have a bad clutch. I suspect you have a bad clutch. You could have the correct voltage going to the clutch but if the clutch has worn the air gap may be to large for the clutch to engage.

yep I did the same. Tested at fuse box nothing, but after I gave the clutch a tap with a hammer it engaged. Sprayed with lithium grease, pray it works😃

I tried to get the clutch to engage by jumpering the low pressure switch....would not. Made sure the clutch worked by applying +12V across the clutch terminals. Added an entire can of the DIY before I saw the clutch engage and compressor short cycle.

This told me that the system was not low, but empty of R-134a.

Starting looking for the leak and found that the high pressure fitting was leaking.
I replaced it...they are cheap....also replaced the accumulator/dryer...took it to a shop so they could evacuate the system and recharge it.

Been cool since.

In your model the low pressure and high pressure switches are not in the path of the compressor clutch power, they are normally closed switches in the path of the PCM control circuits (2 different circuits). Power for the compressor clutch comes from the relay on the dk green wire. When you call for cooling do you have 12V on the green wire at the compressor clutch? If so, replace the clutch/compressor. If not, we'll continue.

George