Skip the auto shop - Our mechanics make house calls

Q: Hear knocking when air conditioning is on

asked by on

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Loss of power steering at random times?

Hello. We'll be happy to answer your question. The recall that you have not completed is most likely while your power steering has an intermittent failure. In may of 2015 Ford announced the recall of an estimated 400,000 models; 2011...

Q: How Does Climate Control Differ From Air Conditioning?

Climate control and air conditioning are terms that are very often used interchangeably. These two systems are related, but they are not the same. The climate control system is used to achieve and maintain a temperature inside a vehicle that...

Q: Service power steering

The cost to repair will depend on exactly what is wrong. The only way to find out exactly what has malfunctioned is to have the power steering system diagnosed. The good news is, if you avail yourself of a mobile...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...