Q: AC knocking when it is turned 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.
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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.
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