240 '93 240 - Loud squealing coming from AC compressor

Hey all, just bought a 1993 240 sedan. It's in pretty good shape except the air conditioning doesn't work. Picked up a DIY AC recharge kit to try and fix it but when I went to turn on the AC today to recharge the system this horrible squealing noise started coming from the compressor.

I can see the compressor clutch and the belt going from the compressor to the power steering pump slow down when the squealing starts which makes me think it's either the clutch or the bearings on their last legs.

The squealing sort of comes and goes, and when the noise stops the pressure gauge on the AC recharge bottle goes up, even if the compressor clutch is engaged. When I turned the throttle on the engine it got even louder. Seriously, it's ear piercing, way worse than a loose fan belt which I experienced on my last 240.

When I went to look at the car before I bought it last week I probably had the AC on for 5 minutes and I could hear it cycling on and off but no cold air was coming out. There was also no squealing coming from the compressor at that time, the noise just started today (even before I tried to recharge the system).

Any ideas? It's getting real hot and humid here in Michigan.

If you want ac to work it's time to replace compressor. If you don't have vacuums pump, take it to a shop and have them vacuum down the system and refill the r134a to the correct weight.

These systems only have a low side port. There is also no way to know how much 134 is in there. So it's easy to overfill the system if you just try to charge it. I just had my system vacuumed down and refilled as described above. There was only .8 of a lb in the system. There is no way of knowing that unless it's vacuumed out and weighed. So I paid the man at the shop.

You may have so much 134 in there that you are over loading the system. Of it could also be a failing clutch. The compressors do fail on these. When I got my system running in my 93 wagon in 2005 it needed a compressor. Every few years enough 134 leaks out the system needed to be vacuumed down, what remained in the system is removed and then the correct amount returned.

Are you sure it's not the belt? How tight is the belt, how dry rotted is it?

If it's a '93, it should have factory R134a, which means both low and high pressure switches (I'm not sure if -92 cars had low pressure switches or not). Which means it must have had 'some' R134a in it for it to be cycling on and off. Cycling on and off quickly generally means that it's low on refrigerant - the compressor kicks on, pumps most of over to the high side, then the low side pressure drops too low and it shuts off.

It's possible that the belt just needs to be tightened, but I'm guessing it's because you just tried to add refrigerant to a long dead system full of moisture. If you do not draw a vacuum on the system, you will have water inside that does not want to compress. Moisture is a pump killer for sure. I wouldn't run the AC anymore or do anything else with it until you have means to draw a vacuum on the system. While you're at it, you'll want to replace the accumulator and orifice tube as well. They should be cheap, and will help ensure a long term repair.

As for not having a high side fitting, that kinda sucks because you'll want to suck down both sides.

When I was an AC newbie, I tried just filling my El Camino with a can full of R-134a. The pump squealed really bad just like you're describing. It didn't help that I was trying to charge an R-12 system without replacing the mineral oil with ester, so that could have been my problem too. Either way, I'd get gauges and a vacuum pump.

For improved a/c you can upgrade to the variable orifice valve. It's a bit more money but still very affordable. I think mine was about $25 when I bought it.

Look at the pulley from the side of the car and you will see how misaligned it is. The bushings are probably all shot by now.

You want to squirt some oil in there too. I would add an ounce, maybe 2 ounces. You have no idea how much oil is in there. Too little and the compressor will lock up.

I do lots of A/C work now. It took years, but it is easy now. I use a machine to recover, vacuum and then recharge by WEIGHT. You can also feel the hoses to get an idea of how well the system is working. High side gets hot, low side gets cold.

volvowagoon said:

When I was an AC newbie, I tried just filling my El Camino with a can full of R-134a. The pump squealed really bad just like you're describing. It didn't help that I was trying to charge an R-12 system without replacing the mineral oil with ester, so that could have been my problem too. Either way, I'd get gauges and a vacuum pump.

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volvowagoon said:

It's possible that the belt just needs to be tightened, but I'm guessing it's because you just tried to add refrigerant to a long dead system full of moisture. If you do not draw a vacuum on the system, you will have water inside that does not want to compress. Moisture is a pump killer for sure. I wouldn't run the AC anymore or do anything else with it until you have means to draw a vacuum on the system. While you're at it, you'll want to replace the accumulator and orifice tube as well. They should be cheap, and will help ensure a long term repair.

As for not having a high side fitting, that kinda sucks because you'll want to suck down both sides.

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It started squealing before I even put in any refrigerant. I definitely won't run it anymore though, don't want to tear the belt to the power steering pump

akantares said:

It started squealing before I even put in any refrigerant. I definitely won't run it anymore though, don't want to tear the belt to the power steering pump

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Okay, I had to reread the initial post. So you haven't charged it yet? Is it squealing with the compressor clutch disengaged?

JohnMc said:

Are you sure it's not the belt? How tight is the belt, how dry rotted is it?

If it's a '93, it should have factory R134a, which means both low and high pressure switches (I'm not sure if -92 cars had low pressure switches or not). Which means it must have had 'some' R134a in it for it to be cycling on and off. Cycling on and off quickly generally means that it's low on refrigerant - the compressor kicks on, pumps most of over to the high side, then the low side pressure drops too low and it shuts off.

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the 6 1993's I have owned only have low pressure ports

edit, reread switches.

You can try spraying WD-40 down there while it squeals. That could tell you something. Cycling does not necessarily mean that the system is fully charged though. Most of the cars I've done didn't start getting noticably cold until they were almost full.

volvowagoon said:

Okay, I had to reread the initial post. So you haven't charged it yet? Is it squealing with the compressor clutch disengaged?

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I put a little bit of refrigerant in to see if that helped the issue since I know those AC Pro bottles have some sort of lubricant in them as well. It does not squeal when the compressor isn?t engaged.

Again, jumping too far ahead. You haven't eliminated a loose or faulty belt. My 940 compressor is slightly out of line with the crank pulley. New mounting bushings did not change anything. I have to change the belt every 12 - 18 months just because of the squealing. Simple test: use a spray bottle and slightly mist the compressor pulley. If the squealing stops replace the belt. Another clue is the pitch of the squealing. A loose belt will squeal at the same pitch no matter what engine rpm. That's a mysterious fact of the universe.

Lazarus

Lazarus said:

Again, jumping too far ahead. You haven't eliminated a loose or faulty belt. My 940 compressor is slightly out of line with the crank pulley. New mounting bushings did not change anything. I have to change the belt every 12 - 18 months just because of the squealing. Simple test: use a spray bottle and slightly mist the compressor pulley. If the squealing stops replace the belt. Another clue is the pitch of the squealing. A loose belt will squeal at the same pitch no matter what engine rpm. That's a mysterious fact of the universe.

Lazarus

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I will try this, thank you!