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edhunt0r, ASE Certified Technician
Category: GMC
Satisfied Customers: 505
Experience:  GM B Tech ASE Certified Master Tech ASE Certified Master Medium/Heavy Truck Technician New Jersey
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A/c blows warm air on passenger side after I left the

Customer Question

A/c blows warm air on passenger side after I left the battery disconnected for several months and then reconnected it.
Submitted: 2 years ago.
Category: GMC
Customer: replied 2 years ago.
Here is some moore info for clarification since I have had zero response for 3 days. Cold air comes only from the driver side vents and at the same time hot air comes from the passenger side when the A/C is turned on. Punching the mode button numerous times fails to correct this with windshield, floor or mid range setting. 2003 Envoy SLT with everything else working just fine. A/C has and still works fine. Internet posts suggest an actuator problem that controls a baffle. Possibly caused by disconnecting the battery and reconnecting the battery after we were gone for several months. Absolutely no problem prior to this. Dealer service department suggested a baffle was stuck and would cost several hundred dollars to fix. Internet post suggests the actuator needs to be reset or rebooted but I am not sure how to do this. Hesitant to touch ground to the positive pole as one person suggested.Any ideas what the problem is? Is the baffle physically stuck or is the actuator that controls the baffle locked up?
Any ideas how to reset or reboot the actuator or free the baffle? Can I replace the actuator or baffle myself?If you want quick answers to multiple questions to try and diagnose this issue just call me.
I am in Seattle on Pacific Daylight Time. (###) ###-####Any kind of help would be appreciated.
Customer: replied 2 years ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  edhunt0r replied 2 years ago.

Hello. Welcome to the site. Thanks for coming.

I'm ***** *****.
I'm here to provide as much information and insight as I can, to best answer your question.

It is probably a bad right temperature actuator.

Do you have access to a scan tool that can check for codes in the HVAC system?

Customer: replied 2 years ago.
Customer: replied 2 years ago.
Can it be reset? This was immediately a problem after the battery was reconnected. This was the first time I have left the battery disconnected.
Expert:  edhunt0r replied 2 years ago.

There is a reset procedure you can try. It states to clear the codes, but try it without because you do not have a scanner.

Alternate Method (w/o Scan Tool)
1. Clear all DTCs.
2. Place the ignition switch to the OFF position.
3. Remove the HVAC B fuse(in rear fuse box under seat)for a minimum of 10 seconds.
4. Install the HVAC B fuse.
5. Start the vehicle.
6. Wait 40 seconds for the HVAC control module to self-calibrate.

Customer: replied 2 years ago.
What are DTCs and how do I clear them?
The actuator is already installed. Is this an issue before I start.
Expert:  edhunt0r replied 2 years ago.
DTC's are Diagnostic Trouble Codes.
When you do the recalibration it should clear the codes unless there is still a problem with the system.
It requires a scan tool that can read codes in the HVAC system.
Customer: replied 2 years ago.
Tried your directions three times with no results. Is there any other way to reset?
Expert:  edhunt0r replied 2 years ago.
Only with a scan tool that has the capability to access the HVAC system aND perform the function test.
One thing you can try which might work is what they call a global reset.
Disconnect both battery cables and touch them together for about 30 seconds, then reconnect them and see if that works.
Customer: replied 2 years ago.
That sounds dangerous.
Please explain.
Expert:  edhunt0r replied 2 years ago.
It's not. The battery will not be connected. It's a new term our GM Tech support uses. By touching the two cables together it drains all the voltage out of the system. Almost like doing a Reboot on your home computer.
Expert:  edhunt0r replied 2 years ago.

Hi, Just wanted to get an update on how you made out with vehicle.

If you need more help, please use the "Reply" tab to continue our conversation - I'm happy to answer follow-up questions.

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