Symptoms of a Bad or Failing AC Belt

The AC belt is probably the most simple component of a vehicle's AC system, but still a very important one. The belt connects the AC compressor clutch to the engine crankshaft, which allows the compressor to be turned via the engine's power when activated. As with most automotive belts, the AC belt will either be a V-belt or a serpentine. A serpentine belt is flat and ribbed, and serves to connect several components, while a V-belt is narrower, shaped like a V, and connects only two components. Whatever the case, when the AC belt fails, or begins to fail, it will display symptoms that will alert the driver that the belt needs to be replaced.

1. Squealing noises when AC is on

One of the most obvious signs that a belt needs to be replaced is that it will produce a loud squealing noise when the AC is turned on. In some cases, this may be attributed to a loose belt, or perhaps water or oil contamination. However, in other cases this may be attributed to a severely worn belt that can no longer properly grip the pulleys. When the belt can no longer grip the pulleys properly, it will slip under the torque of the engine and squeal. Often times this squeal will be very high pitched and noticeable. This is probably the most obvious sign that the AC belt requires attention.

2. Cracks in the AC belt

Another more visual symptom indicating that the AC belt needs to be replaced is that cracks will begin to form on the belt. The longer a belt has been in service, the more heat and wear it has been exposed to, which will eventually lead to dryness and cracking of the belt. An old belt will not grip properly and will actually be a lot more susceptible to breaking than a newer belt. If a belt is showing cracks then it should be replaced.

3. AC belt breaks

Another obvious sign that the AC belt needs to be replaced is the belt snapping. Old belts will snap simply because they are weakened by age and service. You can notice that a belt has snapped because the AC will not function when activated. A quick visual inspection of the belt should be able to identify if it has broken and needs to be replaced.

4. Inability to defrost windshield

Another less common symptom indicating that the AC belt needs to be replaced is the windshield defroster not working properly. The defrosters in some vehicles are connected to the air conditioning system and will require the AC compressor to function for the defroster to work. If the belt snaps or is slipping, then neither the AC compressor nor the defroster will work.

While the AC belt is a very simple component, it is very important to the operation of the AC system. If you suspect that you may be having a problem with the belt, or need to have your AC belt replaced, this is something that any professional technician, such as one from YourMechanic, should be able to take care of for you.


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Ben

41 years of experience
1320 reviews
Ben
41 years of experience
Volkswagen Beetle L5-2.5L - Heating AC - Houston, Texas
i am well satisfied with Mr Smith working on my car(s). He replaced the Jaguar fuel pump like an expert, and then he diagnosed the VW bug ac compressor and fixed it on the spot. I would recommend him to anyone with a car issue
Nissan Altima - Heating AC - Houston, Texas
Incredibly nice and took the time to show me the problem, including comparison pictures between my unit and what a new unit should look like.

Peter

43 years of experience
1321 reviews
Peter
43 years of experience
Saab 9-3 L4-2.0L Turbo - Heating AC - Phoenix, Arizona
He knows what he's doing. Very polite and explained everything. I would no doubt use him again. I highly recommend him.
Mazda Miata - Heating AC - Peoria, Arizona
We are so thrilled to have found Peter as our new mechanic. He is very thorough and knowledgeable. He is also friendly, professional, and extremely honest. He explained to us exactly what services were needed on our vehicle to repair the air conditioner and provided us with an written estimate of the cost. He literally saved us thousands of dollars in repair costs. A local major competitor quoted us a repair cost of a minimum of $1,400 and said that the cost would go up to $2,400 if they discovered an additional part was required. Peter charged us only $202, plus performed the work at our home. The air conditioner in our 2004 Mazda Miata has honestly never worked so great--it always blew out warm air. We just assumed it was how that particular car was manufactured. We would highly recommend Peter to anyone who is in need of an experienced and honest mechanic.

Manuel

32 years of experience
531 reviews
Manuel
32 years of experience
Ford Taurus V6-3.0L - Heating AC - Long Beach, California
Good guy. Knows his stuff. Knowledgeable and straightforward with diagnostics and repair costs. I’d love to work with him again! Thank you Manuel!

Charles

27 years of experience
32 reviews
Charles
27 years of experience
Jeep Grand Cherokee V6-3.6L - Heating AC Inspection - Van Nuys, California
Charles called the day before the appointment to touch base and answer any questions. The next day Charles was on time with a great attitude, explained exactly what was going on and we talked about our next step and confirmed our appointment to actually do the work the following week. All good.

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