Skip the auto shop - Our mechanics make house calls

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.

A: The A/C compressor has an electrically cont...

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?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: What do I do if the moon roof won’t close properly?

There is a possibility that when you try to close your moon roof, it will close and then re-open slightly. If this happens, stop your vehicle, and perform the relearning process for the moon roof. Press and hold the CLOSE...

Q: A/C compressor needs to be replaced on my 2008 Infinity M35. Would you save money and use an after market part or use Infiniti? 2008 Infiniti M35

Hi there - there is actually a 3rd answer that is best. Infiniti doesn't make AC compressors (nor does most any other auto manufacturer). These are made by 4Seasons, Sanyo, Denso, Hitachi, etc. Replacing the compressor correctly means getting an...

Q: Driving down the road in 2013 Nissan altima coupe and the vehicle stopped pulling on its own.

Hi there. If you have replace the sensor and the codes are coming back on, the there could be an issue with the shift solenoids inside the transmission. The code P0500 is coming up for the output shaft speed sensor...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...