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Ask Dave Nova Your Own Question
Dave Nova
Dave Nova, Chevrolet Technician
Category: Chevy
Satisfied Customers: 19450
Experience:  ASE Master Certification. GM World Class Certification
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The blend door actuator keeps cycling. There are no broken

Customer Question

The blend door actuator keeps cycling. There are no broken gears. Could it have other problems or does something need to be reset?
The problem started after I had the radio replaced.
Submitted: 1 year ago.
Category: Chevy
Expert:  Dave Nova replied 1 year ago.

Does the actuator repeatedly click click click....

Customer: replied 1 year ago.
No it continually moves the blend door back and forth, will not stop in center.
Expert:  Dave Nova replied 1 year ago.

What is the model of your 1999 Chevrolet?

Customer: replied 1 year ago.
Blazer LT
Customer: replied 1 year ago.
with*****
Customer: replied 1 year ago.
Reinstalled the actuator and it is clicking
Customer: replied 1 year ago.
Is anybody there?
Expert:  Dave Nova replied 1 year ago.

Sorry for the delay. This is the temperature actuator, correct?

Customer: replied 1 year ago.
the one that regulates the blend door.
Expert:  Dave Nova replied 1 year ago.

Was the battery disconnected when the radio was replaced?

Customer: replied 1 year ago.
it was.
Expert:  Dave Nova replied 1 year ago.

Try disconnecting the battery again. Reconnect and then turn key on. Do not touch any a/c controls for two full minutes. Actuator should cycle to relearn the travel limits, then should stop. Let me know what it does.

Customer: replied 1 year ago.
I will have to do that in the morning. Will send an email as soon as I finish.
Expert:  Dave Nova replied 1 year ago.

Sounds good. Will look forward to your response.

Customer: replied 1 year ago.
Dave,I disconnected the battery and did the procedure twice and it is still moving about every five seconds and does not stop in the center. This problem appeared after the radio was installed. They took it to a repair shop that said the gear in the actuator was bad and they were to install a new one. It appears that all they did was get the door in the center then unplug the actuator. When the heat would not work I took it to a dealer who said the actuator was bad and needed to be replaced. The gears look fine to me, no visible cracks or missing pieces. Is there a possibility that the electronics inside the actuator have a problem?
Customer: replied 1 year ago.
I tried a third time leaving the battery disconnected for a longer time. I put my finger on the hole in the actuator and the cycling did not appear to happen after the key was on for two minutes. However, after I turned it off and started the car it started cycling again. Could the temperature control be defective?
Expert:  Dave Nova replied 1 year ago.

The problem could be in the actuator, or in the electronic control in the dash. The actuator provides feedback to the control module so that the module knows the position of the actuator. The most likely problem is a failed feedback potentiometer within the actuator.

Customer: replied 1 year ago.
I am going to order a new actuator. When I install should I disconnect the battery and then reset?
Expert:  Dave Nova replied 1 year ago.

Yes, either disconnect the battery or pull the main HVAC fuse.