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Q: Hear knocking when air conditioning is on

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I hear a knocking on the front passenger's side when the air conditioning is turned on. Could it be the air conditioning actuator?

Hello. The air conditioning systems in modern cars use little electric motors that move the doors inside the heater box that regulate temperature and where the air is discharged. When the motors break internally or a door breaks past a stop, there will be a clicking noise emitted. So to answer your question, yes, it could be an actuator motor. Once it’s determined which actuator is noisy, the actuator can be removed, and whichever door it’s connected to can be moved by hand to check the stops. If the stops are good, then there’s a good chance that the actuator motor needs to be replaced. Have a mechanic diagnose your AC’s noises and verify this issue in order to move on to repairs.

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