Q: AC knocking when it is turned on

asked by on

I think there is either a problem with the blower or fan belt. When the air conditioner is turned on, it starts making a catching/knocking sound. As soon as it is turned off, it stops.

Hi there. It sounds to me as if your AC’s fan is interfering with something in the track of its spinning. Also your issue can point to your AC compressor clutch not gripping the pulley correctly. I’d suggest having a certified mechanic sent by YourMechanic come to your residence and correctly diagnose the air conditioner’s symptoms that your vehicle is experiencing.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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
  1. Home
  2. Questions
  3. AC knocking when it is turned on

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: Ac hot air. 2001 Dodge Stratus

Hi there. You should begin by finding the leak in order to determine what it would take to fix it. Adding refrigerant to the system may make it work now but you could overcharge it and cause more problems in...

Q: Thumping noise when turning right

Hey there: It's quite possible that a stabilizer bar bushing might be the source of this knocking sound when you turn right. It's also possible that the noise is coming from an upper or lower strut mount that is worn...

Q: Are strut mounts typically replaced when you do new struts on front end? Quoted $700+tax for both - not including alignment. High?

Hi there. Were the mounts quoted in the estimate? Was a strut assembly quoted? If the answer is no to these questions, then the strut mounts were not quoted. However, the strut mounts on this vehicle are pretty much just...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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.