A/C blows air in reverse when car unlock?

DRFIROJTADAVI

MEMBER
2010 GMC ACADIA
3.6L
V6
4WD
AUTOMATIC
89,000 MILES

This is intermittent issue when I am switch off the A/C and engine and then locks the car by remote keys in parking and come back after 1 or 2 hours. When I unlock the car by remote key and enter in the car the air is blowing out the from the inlets with full speed, but the A/C buttons switch not on and keys in my hand but when I insert the key in ignition the blower will stop blowing air from inlet. Kindly help me about this issue. Thanks

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5 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

That is really odd. I'm questioning if the ignition switch is the issue. When this happens, what happens if you wiggle the switch without turning it on?

Also, you may want to consider having the system can-scanned. This type of scan will retrieve diagnostic trouble codes regardless of the module storing them.

Here is a link showing how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know.

Joe

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Monday, May 29th, 2023 AT 7:26 PM

DRFIROJTADAVI

MEMBER
33 POSTS

Thanks for your reply.
Mostly 8/10 time happens in hot climates around 45 degrees Celsius.
Wiggling the switch, nothing happens.

My understanding is that the air coming out from the inlet vent which supposed to sucks the air inside of the car and send to evaporator and cool’s the air and send this air out from A/C vent, some how this works in reverse like you change the electrical polarization and the fan rotating in opposite direction. I have attached the can scan report kindly look at it. Thanks

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Tuesday, May 30th, 2023 AT 6:52 AM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

Based on what you said, it does sound like the polarity is being reversed.

I looked up the codes, and both require me to know if this has automatic climate control or manual control.

Sorry about that. Could you let me know?

Joe

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Tuesday, May 30th, 2023 AT 9:25 PM

DRFIROJTADAVI

MEMBER
33 POSTS

This is manual control sir.

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Tuesday, May 30th, 2023 AT 10:04 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

I looked up each code for the manual climate control and both appear to be related to airflow direction. See below.

B3779 08
Air Flow Control 9 Circuit Actuator Stalled

B3782 08
Air Flow Control 10 Circuit Actuator Stalled

The airflow direction is controlled by a mode door actuator. However, that wouldn't cause the issue described. I have a feeling the module itself has failed.

The first thing indicated in the manual is to recalibrate the actuators. I attached directions below. Take a look and let me know if you are comfortable performing it. Note there are two ways to do it. You can use a scan tool or do it manually.

Let me know.

Take care,

Joe

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