Truck running switch on the A/C it starts squealing really loud?

BOBBYBOY76

MEMBER
2009 CHEVROLET SILVERADO
5.3L
V8
2WD
160,000 MILES

I really need some help with this. When my truck is running and I switch on the a/c it starts squealing really loud. Like I think the compressor clutch stops or maybe is hesitating. I've already changed out the compressor, tensioner pulley, and belts but it still hasn't fixed the issue. Does someone have any other ideas?

7 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

If it only happens when you turn on the AC, the compressor sounds like it is locked up. You indicated the installation of a new compressor. If you disconnect the power lead to the compressor, does it still make the noise?

Also, if everything is new, there could be an issue with too much PAG oil, or it could be overcharged. Let me know what and how things were done to recharge the system after the replacement compressor was installed.

Take care,

Joe

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Sunday, August 25th, 2024 AT 8:07 PM

BOBBYBOY76

MEMBER
4 POSTS

On a cold start it will squeal for a couple seconds and then quit but other than that it only does it when A/C is on. After the compressor installed, which I bought brand new, it was vacuumed and then charged with the amount of refrigerant specified. It was reading good on the gauges. It was supposed to have some compressor oil in the compressor when I bought it but when I tried draining it only a couple drops came out. So, I then put 4 oz of compressor oil in the compressor, installed it, and after the refrigerant charge I put three more oz of oil. And to answer your question, no it doesn't squeal with the compressor unplugged.

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Monday, August 26th, 2024 AT 6:16 PM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

I have a feeling there is too much PAG oil in it. The entire system only holds 7.1 ounces. You added 7 ounces to what was still in the system.

If the refrigerant is properly charged, either there is too much oil, or the new compressor is locking up.

Joe

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Monday, August 26th, 2024 AT 8:10 PM

BOBBYBOY76

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4 POSTS

I will check and let you know what I find out.

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Monday, August 26th, 2024 AT 11:14 PM

KEN L

MASTER CERTIFIED MECHANIC
47,536 POSTS

This takes a special belt, it's like a rubber band, you must get the right one or it will squeak. Here are the instructions. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.

Images (Click to make bigger)