Q: Squealing from AC Clutch

asked by on

With the vehicle in idle and the AC on Max AC the vehicle has an intermittent squealing sound. Vehicle is in Park. If I take the Max AC off the AC blows warm air. If Max AC on the Air is cold. Please help.

My car has 98000 miles.
My car has an automatic transmission.

The A/C compressor has an electrically controlled clutch mechanism, part of which is visible. The clutch is adjacent to the A/C compressor pulley that has the serpentine belt on it.

When the car is running, and A/C is off you should see the pulley only turning. As you view the pulley turning, have an assistant turn the A/C on max. Make sure car is in park with emergency brake on and wheels are blocked. Do not stand in front of the car, stand to the side.

When your assistant turns A/C on max (blower on, too) you should see the clutch turn with the pulley. That signifies that the compressor is at least "turning" as the clutch is now locked to the pulley.

Now, have the assistant turn max "off" (i.e., use regular A/C setting). The clutch should still be engaged and turning with the pulley, although the clutch might cycle on and off which is normal as the cooling load will vary. If the clutch does not engage with the "normal A/C" setting there is a problem, possibly electrical but also possibly related to the level of refrigerant charge.

You should check the refrigerant charge using a manifold to confirm that pressures are within normal range (if pressures are too low, there is a switch in the system that will shut down the compressor because low pressure does not adequately lubricate the compressor; it is a safety switch).

The squealing sound could have a variety of causes: A/C clutch slipping (in turn would have a variety of causes); belt is damaged, old and worn; misaligned belt pulleys including that on harmonic crankshaft balancer; damaged or dried out (grease) pulley bearings; A/C compressor shaft bearing is bad.

If you feel like this repair may be over your head, have one of our mobile technicians perform these checks and diagnose the issue with your A/C system for an accurate repair. Best of luck.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Squealing from AC Clutch

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: 2000 Toyota 4runner-both oxygen sensor replacement

If you input your year, make and model, as well as location (zip code) at YourMechanic's oxygen sensor replacement service page, the exact written quote you desire will be provided. Generally, after about 100,000 miles of use, it's not a...

Q: My actuator works backwards

Hello. We will need to observe several other factors in order to pinpoint what the issue is. When you say you are turning on the vents, what setting are you turning on when this happens? Is it all temperature settings...

Q: Q: check engine light on

There is a special service campaign from the manufacturer for this problem. Your vehicle may be covered for the repair under service bulletin number 15824-01 dated August 9th 2016. The bulletin covers codes P0010 and P0013 for the intake or...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.