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Old 08-19-2017, 05:18 PM   #1
71C10Guy
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Ac compressor squeal?

Okay, so I have completely redone my AC system. My low pressure switch does not work, and really none of the circuitry to the compressor works. I have it wired to a switch on my dash to engage the magnetic clutch. Everything is brand new.

So when I turn my compressor on at idle it will run fine for about 30 seconds before it starts seizing. The belt slips on the compressor pulley and makes a horrible squealing noise. This also practically stops my water pump and fan. Once it starts it will not stop until I disengage the clutch. If I am not idling, even if it is just a hundred rpm over idle, the compressor immediately seizes and squeals.

I cannot figure this out. Everything is new including lines, the compressor came with oil in it and I put more oil in because I had a leak that let out about half of the original freon. I have retightened the belt twice, one person pulling their whole body weight on the compressor and the other tightening bolts. I don't see how I can have dirt in my freon, and the belt definitely isn't loose.

The only plausible thing I can think of is the high side of the gauge I used is leaking so I did not hook it up, therefore I do not know what the high side is when running. Low side is at 30 when running. I am running R134a.
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Old 08-19-2017, 06:04 PM   #2
leddzepp
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Re: Ac compressor squeal?

Does the belt ride inside the pulley, seated way down in the groove? If so, it will continue to slip. Try a wider belt so that it rides slightly on the outside lip of the pulley. Post a pic if you can.
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Old 08-19-2017, 06:12 PM   #3
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Re: Ac compressor squeal?

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Originally Posted by leddzepp View Post
Does the belt ride inside the pulley, seated way down in the groove? If so, it will continue to slip. Try a wider belt so that it rides slightly on the outside lip of the pulley. Post a pic if you can.

Kind of? And why would the belt riding lower cause it to squeal?
Thank you!
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Old 08-19-2017, 06:38 PM   #4
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Re: Ac compressor squeal?

Here is the belt I'm running, see how it sits outside the pulley slightly? Sitting inside it will slip, it has better contact on the edges.
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Old 08-19-2017, 06:39 PM   #5
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Re: Ac compressor squeal?

Part number. 350 with factory air, a10 upgraded compressor.
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Old 08-19-2017, 06:42 PM   #6
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Re: Ac compressor squeal?

Once you start driving and air blows through the condenser your pressures will drop and there will less stress on the compressor as well.
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Old 08-19-2017, 06:52 PM   #7
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Re: Ac compressor squeal?

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Originally Posted by leddzepp View Post
Once you start driving and air blows through the condenser your pressures will drop and there will less stress on the compressor as well.
That's why I mentioned the rpm, if I'm driving down the road it will immediately squeal. The only time it doesn't is low rpm. I guess I could put it in neutral and coast, then try to slowly raise the rpm, but I don't think it will help.
Thanks anyways though.
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Old 08-20-2017, 12:07 PM   #8
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Re: Ac compressor squeal?

It shouldn't squeal even if you were driving on the freeway and turned the compressor on. Something is wrong with the compressor, is my guess.
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Old 08-20-2017, 02:05 PM   #9
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Re: Ac compressor squeal?

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It shouldn't squeal even if you were driving on the freeway and turned the compressor on. Something is wrong with the compressor, is my guess.
Okay, I figured it out. For one, there was a piece of debris in the expansion valve that I guess escaped the system flush. It was making the high side skyrocket and the low side too low. Also, we retightened my belt using a crow bar, and that thing is tight!

Everything seems to be working, I'm not getting anything below 65, but on a 100 degree day I don't even care, it's better than what I had before. So thanks for your input guys.
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Old 08-20-2017, 02:50 PM   #10
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Re: Ac compressor squeal?

>> I have retightened the belt twice, one person pulling their whole body weight on the compressor and the other tightening bolts.<<
>>Also, we retightened my belt using a crow bar, and that thing is tight! <<

How long do you expect the clutch bearing to last?

>>debris... was making the high side skyrocket and the low side too low.<<

I thought you couldn't check the high side before, because of leaking gauge set?

What are the pressures now?

If I had re-opened the system, I would have made an attempt at determining exactly how much oil was in there. You indicated that you had not verified the actual amount of oil in the new compressor and then added some after a leak.

Correct refrigerant amount with lower pressures and the correct amount of oil would make me think belt slipping would no longer be an issue.
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Old 08-20-2017, 11:03 PM   #11
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Re: Ac compressor squeal?

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Originally Posted by 71C10Guy View Post
Okay, I figured it out. For one, there was a piece of debris in the expansion valve that I guess escaped the system flush. It was making the high side skyrocket and the low side too low. Also, we retightened my belt using a crow bar, and that thing is tight!

Everything seems to be working, I'm not getting anything below 65, but on a 100 degree day I don't even care, it's better than what I had before. So thanks for your input guys.
Like RichardJ says, you are going to take out some bearings with that kind of belt tension. More attention is needed to get to the root cause of the issue.
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Old 08-21-2017, 11:26 PM   #12
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Re: Ac compressor squeal?

on a 100 degree day and your outlets at 65 is good. R134 from memory was a minimum 23 degree drop from ambient, 27 degree minimum drop with r12. I did a fair share of ac work up north here and if i serviced a system, when i had the refrigerant removed i would remove the manifold at the rear of the compressor. This is easy to do and tells you a lot about the health of the system. The low side return should have a oil film if you took your pinky and dragged it around inside the manifold. I would do the same on the high side discharge port with my pinky and check for a gray metallic dusting present. If it was dry on the suction side and gray on the discharge side the compressor is being stressed, obviously not yours being new.

It sounds like you added enough oil, but still good to check if opened up. Remember that until the receiver drier (accumulator in gm words) has oil in the bottom, there isn't anything to get misted up to the compressor from the dip tube built into it.

Refrigerant oil is like ground circuits in electrical work, the forgotten element!
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Old 08-22-2017, 12:21 AM   #13
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Re: Ac compressor squeal?

Did the compressor come with oil type and "balancing" instructions ? The compressor can have too much oil and incorrect oil also. How long did you vacuum the system before charging refrigerant ? I would Try a laser if available to check pulley alignment for the belt squeal, but I would not tighten as tight as described. I would drain the compressor and add the oil spec indicated for the compressor. It may have too much oil. Since you wired the clutch, I would take off the belt, turn the clutch on and see how difficult it is to turn by hand. You should be able to turn it without too much extreme effort. Is it an orifice tube ? Is it the same orifice for R134a vs. R12 ?..it sounds to me like a bad A/C compressor...but that's just my .02 cents...
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