How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask George H. Your Own Question
George H.
George H., ASE Certified Technician
Category: Car
Satisfied Customers: 18768
Experience:  ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
Type Your Car Question Here...
George H. is online now
A new question is answered every 9 seconds

My Pontiac g6 makes an atrocious knocking noise. I think it

This answer was rated:

My Pontiac g6 makes an atrocious knocking noise. I think it is the flap that controls inside and outside air. The only way to get the noise to stop is by changing the air flow to a non defrost position and change it to inside air flow.

Hello I will help you with your question,

The recirc door actuator has lost its feedback to the HVAC controls and will need to be replaced.

The procedure to replace this part is below, once you remove it turn the shaft of the door by hand to feel that it is not broken. If you do feel a broken door you will need to remove the HVAC housing to repair it but it usually is the actuator. Inspect the cabin air filter and replace if it is deformed as well.

Click here for procedure

Let me know how I can help you with this

Thank you

Customer: replied 4 years ago.

What parts will I need to purchase? And is this a job that I could do or needs to be taken in for repair?

YOu can use the procedure and replace th actuator yourself. You only need to door actuator. NAPA or the dealer will have it. Pull yours if you go to NAPA so they can match the part number

Sorry I was thinking of a different application that has a cabin filter. Yours does not.

The actuator for the recirc door should be the problem here, you can check by switching from outside to inside air and if that changes the noise that is the actuator.

Let me know how I can help


Customer: replied 4 years ago.

Okay. Would a place like Napa or autozone do a this? And it switches from outside to inside air fine, so I will just need to replace the actuator?

NAPA would have the part, Autozone will not. A NAPA affiliated repair shop would be able to replace the actuator for you. Expect to pay $200 - $250 to have the shop do the repair..

If the noise changes when you switch from inside to outside and the airflow switches then you only need to replace the recirc actuator. If changing the point the air exits the vents is what changes the noise that is a different actuator but still an actuator problem.

Please help me get on the same page by letting me know if it is the inside/outside control that changes the noise or if it is strictly changing from floor to defrost.

Thank you

Customer: replied 4 years ago.

Okay. This is how it works. I turn my car on and the car defaults to outside air. The knocking noise starts immediately and then I switch to inside air. The car only allows inside air from a non defrost flow setting. So basically once I turn it to inside air from outside the noise stops. You said a repair would cost around 200 or up, do u have an idea of the cost of the part?

OK, that is how I was understanding it. The part is about $120 and takes 1/2 hour to install. If the shop buys and installs the part they will charge a diagnostic fee so the part and labor would be $200 - $250 installed depending on what the hourly rate is.

Please let me know how I Can help


George H. and other Car Specialists are ready to help you