1986 GL. Had to replace my AC condensor during the summer due to a fence poking through it (long story). The AC was original R12 and worked well. Of course, the system is now depressurized. I want to convert to 134a when I recharge. My girlfriend has tried to turn on the AC a few times and she says that there is a terrible squeal for about 3-5 seconds. I'm guessing that the compressor won't run due to lack of oil and refrigerant and that's causing the squeal. I definitely don't want to run it dry as she did a couple of times, but I need to know if the compressor will run before I recharge so that I don't waste a recharge kit. Any ideas of how to test the compressor before I recharge? Again, it worked fine before I changed the condensor. Thanks.

If the system is discharged, then the compressor won't run because the low-pressure switch won't let it. Did you recharge w/ R12 when you replaced the condenser?

No, it hasn't been recharged yet.

So I added refrigerant to the low side today. Reading 45psi-right at the maximum allowed pressure according to the gauge. When I pushed the Max AC button, sure enough, the compressor was not turning, the belt was heating up and there was a hell of a squeal. Because this is happening, it sounds as though the low pressure switch is satisfied since the clutch is trying to engage. Is this correct? If so, then the compressor must be locked up. Is there anyway to manually free it up? Can I force it to turn over manually a few times to free it up? Again, the compressor worked fine before I had to replace the condensor. Thanks.

I would apply current directly to the compressor clutch to make sure that it engages properly. Just leave the engine off and make sure that you can see or feel the clutch engaging and disengaging. If it will engage properly, then you can put a strap wrench on the pulley and try to turn it by hand.

 

How long did it sit empty?

Thanks, scoobywagon. I'll try that tomorrow. Should I just use battery voltage at the compressor?

 

It sat empty for many months. I know that's not good, but circumstances forced my to forget about it for a while.

Yes, you can just put current to it directly from the battery.

 

During the time it sat empty, had you left the system under vacuum? It occurs that it is possible that the rotating assembly inside the compressor could have corroded. If so, then the compressor is essentially toast.

BTW, where exactly do I use the strap wrench? At the very front part of the compressor pulley where the tangs are located? (The tangs that the sensor detects).

Strap wrench should go on the pulley directly. In other words, pull the belt off the compressor.

Yeah, the sytem sat uncharged and not under vacuum. I realize that the compressor might be toast, but I'm hoping not. Oh well, at least somebody else might read this thread and avoid the mistakes that I made. I'll update after I get out there to work on it tomorrow.

So the compressor will not turn with the clutch engaged. I used a strap wrench on the pulley. The pulley turned (barely), but the compressor would not. I have one last idea. I see that I can get a pipe wrench onto the clutch plate on the front of the compressor without damaging the sensor tangs. I tried with my 14 inch wrench, but it was slightly too small. Once I get a bigger wrench, I'll try to force it to turn. I can only hope that rocking it back and forth will free it up and allow the refrigerant/oil to circulate again and coat the internal bearings of the compressor.

Your clutch is working, the compressor is toast. If the clutch engaged with no pressure in the system, you have other problems too. It should not do that. The pressure switch is there so the clutch will not engage, the compressor will not turn, so you won't fry your compressor running it without the oil and refrigerant circulating. You need a new, or used compressor, new dryer, properly flushed system, and new oil and freon, and fix that pressure switch, or find out if it's been hardwired, so you don't burn it up again.

All your doing by forcing that thing to turn is tearing it up more. It's easier to remove it, put it on the ground, and hit it with a sledge hammer, after you get your new one in...

Edited November 17, 200916 yr by Frank B