Squealing Sound when heater or AC is turned on

CUGUY8920

MEMBER
JEEP CHEROKEE

So I have a 2000 Jeep Cherokee Sport, 130,000 miles on it and is in very good condition. All for except this disgusting squealing sound I get from the car when the AC or Heater is turned on. Now it only does it if I try to turn the heat or the AC on right after I've just started to car up. It takes about 10 minutes before I can actually turn the heat or AC on, and then it wont squeal. What is it that is making this god aweful noise? A belt? Something else? Thanks for the help!

2 Replies

MERLIN2021

MECHANIC
17,250 POSTS

The squealing sound you are experiencing in your 2000 Jeep Cherokee Sport when you turn on the AC or heater is likely due to a slipping or worn accessory drive belt. The accessory drive belt, also known as the serpentine belt, is responsible for driving various engine accessories, including the air conditioning compressor and the alternator.

When you start the car, the engine places a high load on the accessory drive belt, and if the belt is worn or loose, it may slip on the pulleys, causing the squealing noise. After a few minutes of running, the belt may warm up and gain enough grip on the pulleys, which could be why the squealing stops once the car has been running for a while.

Here are some steps you can take to address the squealing noise:

Inspect the Belt: Open the hood and visually inspect the accessory drive belt for any signs of wear, cracks, fraying, or glazing. Pay attention to the belt's tension; it should not be too loose or too tight.

Check Belt Tension: Most modern vehicles have an automatic belt tensioner that keeps the accessory drive belt at the proper tension. If the tensioner is not functioning correctly or if the belt is not tensioned properly, it can cause slippage and noise.

Replace the Belt: If the belt appears worn or damaged, or if it has been a long time since it was replaced, consider replacing it with a new one. A new belt should provide proper grip and reduce or eliminate the squealing noise.

Check Pulleys: While inspecting the belt, check the condition of the pulleys as well. Worn or misaligned pulleys can also cause belt slippage and noise. If you notice any issues with the pulleys, they may need to be replaced or aligned correctly.

Professional Inspection: If you are unsure about inspecting or replacing the belt yourself, or if the issue persists after replacing the belt, it's best to have the vehicle inspected by a qualified mechanic. They can diagnose the source of the noise more accurately and recommend the appropriate repairs.

It's essential to address the squealing noise promptly because a slipping accessory drive belt can lead to decreased performance of various engine accessories, such as the alternator, power steering pump, and air conditioning compressor. Replacing a worn belt or addressing other belt-related issues can help keep your Jeep Cherokee running smoothly and ensure reliable performance of the accessories driven by the belt.