# Car AC compressor makes whining sound when accelerating
**URL:** https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034
**Category:** Factual Questions
**Created:** [May 17, 2016, 8:57pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034 "2016-05-17T20:57:09Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@BrandonR](https://boards.straightdope.com/u/BrandonR)
#### Post date: [May 17, 2016, 8:57pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/1 "2016-05-17T20:57:09Z")
Hi all!
After my car’s AC being out of service for months due to a leak, I found the leak (high-pressure side fitting) and recharged it.
Now my AC works, but my car makes a weird whining noise whenever the compressor is on and I accelerate. It almost sounds like a hydraulic pump. It gets louder but will suddenly quit after revving for maybe 5-10 seconds, only to return after slowing down and accelerating again or waiting.
I know the compressor is involved because it only happens when AC is switched on.
Any ideas? It’s not squeaky like a belt, and the fact that it can literally stop instantly makes me think something with the compressor clutch?
Car is a 2010 Ford Fusion.
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### Author:  [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)
#### Post date: [May 17, 2016, 10:42pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/2 "2016-05-17T22:42:20Z")
> [@BrandonR](#):
>
> Car is a 2010 Ford Fusion.
Found your problem.
You might have a drive belt slipping, or an issue with the pulley itself (bearings perhaps).
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### Author:  [@JerrySTL](https://boards.straightdope.com/u/JerrySTL)
#### Post date: [May 17, 2016, 10:51pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/3 "2016-05-17T22:51:58Z")
If you just hooked up a can of Freon until things got cold, there’s a good chance that you AC system isn’t properly serviced. The could be especially true if there was no pressure in the AC when it leaked down. You could have moisture in the system or even have too much Freon in it.
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### Author:  [@BrandonR](https://boards.straightdope.com/u/BrandonR)
#### Post date: [May 17, 2016, 10:56pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/4 "2016-05-17T22:56:22Z")
No, we used gauges to ensure proper pressure. Moisture is definitely possible but could that cause this kind of noise?
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### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [May 17, 2016, 11:27pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/5 "2016-05-17T23:27:03Z")
> [@BrandonR](#):
>
> No, we used gauges to ensure proper pressure. Moisture is definitely possible but could that cause this kind of noise?
if you have a leak which causes a total loss of refrigerant, then (moist) outside air can get into the lines. If anything from the outside has made its way into the system, after you repair the leak you need to have it evacuated (held under partial vacuum) for a while before recharging it. Also, if the recharge kit didn’t have the compressor lubricant in the cans of refrigerant, it may be low.
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### Author:  [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)
#### Post date: [May 18, 2016, 1:43am UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/6 "2016-05-18T01:43:40Z")
> [@BrandonR](#):
>
> No, we used gauges to ensure proper pressure. Moisture is definitely possible but could that cause this kind of noise?
You don’t charge an a/c system based on pressure. You test operation by reading pressures. You have to charge an a/c system with the proper amount of Freon that is specified. If you don’t bring it into a proper vacuum before charging the air left in the system can cause high head pressures and make your belt slip or seize your compressor.
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### Author:  [@herman\_and\_bill](https://boards.straightdope.com/u/herman_and_bill)
#### Post date: [May 18, 2016, 12:38pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/7 "2016-05-18T12:38:30Z")
Check the tensioner pully, the bearings will some times go out.
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### Author:  [@Gary\_T](https://boards.straightdope.com/u/Gary_T)
#### Post date: [May 18, 2016, 1:07pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/8 "2016-05-18T13:07:15Z")
> [@BrandonR](#):
>
> No, we used gauges to ensure proper pressure. Moisture is definitely possible but could that cause this kind of noise?
No. The concern with moisture is that it can freeze inside the system and possibly restrict the refrigerant flow, and might lead to corrosion.
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### Author:  [@Isilder](https://boards.straightdope.com/u/Isilder)
#### Post date: [May 20, 2016, 12:12pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/9 "2016-05-20T12:12:52Z")
Doesn’t ice cause this problem ?
The ice inside the cold element constricts flow and makes it squeal inside the car, and makes the compressor go clung clung clung…
After a bit the cold element is heated up by the non-freezing air, and the ice melts…
Then it runs ok for a bit until the ice returns AND the RPM’s means the compressor is pushing faster than the gas can flow through the restriction.
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### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [May 20, 2016, 12:18pm UTC](https://boards.straightdope.com/t/car-ac-compressor-makes-whining-sound-when-accelerating/755034/10 "2016-05-20T12:18:50Z")
> [@Isilder](#):
>
> Doesn’t ice cause this problem ?
> The ice inside the cold element constricts flow and makes it squeal inside the car, and makes the compressor go clung clung clung…
>
> After a bit the cold element is heated up by the non-freezing air, and the ice melts…
> Then it runs ok for a bit until the ice returns AND the RPM’s means the compressor is pushing faster than the gas can flow through the restriction.
there should be no ice inside the system. if there is, the system was not properly evacuated prior to being recharged.