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Q: 2012 GMC Sierra 2500HD No Blend Door Working

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None of the blend doors on my truck will work. I cannot control the vents where the air comes our (ie. floor, dash, defrost). I cannot control the heat on either the driver or passenger side. I cannot control the recirculate function. I have dual zone climate controls.

I had a friend hook up his computer and there are a ton of codes. He was unable to control the HVAC by submitting commands directly from his computer. None of the blend doors will move and all of the codes are related to the blend doors. I think it's highly unlikely that all of them are bad.

During the summer the passenger side would occasionally start pumping heat with the AC on. At that time. I don't recall if any of the other functions would work since I don't drive it very often. I need some ideas.

My car has 54000 miles.
My car has an automatic transmission.

A: Hello, you are going to need a diagnostic c...

Hello, you are going to need a diagnostic chart for this type of issues. The chart gives you a process to a path of repair or replacement for each code. When you have many system codes you would first check power and grounds. An electrical schematic would be required for this. The HVAC control module itself could be at fault. If you'd like, a certified technician from YourMechanic can come to your location to run system tests to diagnose the AC system and perform appropriate repairs as needed.

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