AC pump squealing, I think...

[87ChevyR10]

So, my AC pump has this wierd thing where it squeals like crazy when it's hot and dry out but works fine when it's cooler and wet (no noise).

Any explanations?

 

[350runner]

check you belt may be stretched or have oil on it.

Sent from the dust in front of you!

 

[MadOgre]

Usually the belts break from the pump becoming to difficult to turn AKA seizing. I would remove the belt and ensure by hand that it is not seizing.

 

[87ChevyR10]

Why is the belt always the first response? I had already thought of this; however, I felt the pump is the issue because of the behavior.

Anyways, the pump works when it's wet outside, but squeals when it's dry. Would this indicate the moisture is lubing the pump enough for it work? When it works, it works quite well. A/C system has been converted to the R134a format as well (not by me) and the cycling does not indicate low freon.

I tried to to see what was going on yesterday; but the squealing is loud, I couldn't stick around long enough. I did see the pully turning. But could not tell if it was turning the same speed as the belt or not.

I'll look into it more when I get up later.

 

[87ChevyR10]

Just got back in from watching the belt that drives ac comp. With comp off, the belt looks normal. Very little up/down motion between water pump and ac pump. However, once I turn ac on, the belt has about an inch of up/down motion between water pump and ac comp. So, I guess this confirms my suspicion that the pump is trying to seize. My guess the humidity is helping to lubricate it enough to work normally. I wonder if something like a bearing is dry?

With engine off, the belt tension is pretty solid. Very little give between pullies. The belt itself looks like it's in good shape, too.

What do you think?

 

[350runner]

look at the belt very closely to see if there are any cracks in the clogs. before I'd condemn the compressor I'd check the low side pressure. and change the belt. those two are usually the culprit. if all else fails then compressor it is. https://www.rockauto.com/catalog/moreinfo.php?pk=1333170&cc=1030824&jnid=462&jpid=39

Sent from the dust in front of you!

 

[350runner]

Alright Bud since i now have an electric fan installed... I want to make another assumption. With my Ac I notice that if the truck is not moving, the ambient temps are 100 or close to, and the electric fan isn't on pulling air across the condenser the compressor will lock up. Causing the belt to sequel. Maybe the issue with yours is its not getting enough air flow across the condenser. Does the belt sequel add speeds above 45mph?

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[87ChevyR10]

Yeah, it still squeals at highway speeds. It is only quiet when the humidity is up or it is wet out. Rarely is it quiet at ither times.

 

[350runner]

Ok humidity is moisture that moisture cools the condenser coil down a bit more then usual. How did you first go about putting the refrigerant in the system? Any parts been replaced? It really seems like the high side pressure is a bit too high.

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[350runner]

Also how clean is the condensing coil up front?

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[87ChevyR10]

I havent touched ac system. It was converted by po and he had a new blower fan installed.

I have not looked at condenser coil for cleanliness.

 

[350runner]

Ok when you get time Check the coil. Then test my theory out but using a garden hose. Let the water run for a bit till it cools down. After the water is cool spray the condensing coil for 3-5 mins. After that time the coil will be fully saturated and cool to the touch. Keep spraying and have someone keep the engine idle at approximately 800rpm and turn on the Ac. Does the compressor clutch still seize and belt sequel?

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[87ChevyR10]

Ok, Ill try that later today. Thanks!

 

[350runner]

Your welcome. There's allot of variable but this one is the easiest to test first. And free... Who doesn't like free?

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