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2007 Silverado heater/AC: changes hot to cold vice versa

2007 Silverado climate control system.
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2007 Silverado heater/AC: changes hot to cold vice versa

Postby cfytech [OP] » Feb 10 2021, 7:16pm

Issue is that the heater or AC face outlets may work ok at first but then spontaneously change over to defrost outlet, and usually change from hot to cold or vice versa. Have replaced both actuators (blend door in heater housing and the one under the steering column.) Each time an actuator is replaced the heater/AC system works normally for a few days then reverts back to goofy behavior. Temp gauge steady at 12:00 oclock. Plenty of heat or AC air when it does work.

Sometimes I can get it to work correctly by if I set temp sliders to cold for 30 seconds, then back to hot. Then I hear blend door changing sounds and air comes out of selected face outlets. Sometimes changing outlet selector from face outlets to defroster then back to face outlets gets warm air back to face outlets. But it may or may not change on its own back to defroster after a few or several minutes, and usually changes from hot to cold as well. I'm told defaulting back to defroster outlets is a fail safe, get you home behavior for safety reasons.

Last mechanic says it might be the temp controller, but these are pretty pricey at 400-500 new plus labor.

Anybody know where I can get a diagram of the climate control circuits for a 2007 Silverado Classic, 4.8L, first half year model (with old style dumb ignition key)?
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Posts: 3
Topics: 3
Joined: Mar 23 2019, 10:26pm
Years of membership: 2 years of membership2 years of membership
Location: Montana
Year: 2007
Make/Model: Chevrolet Silverado
Extra Info: Classic
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