clicking under dash

2004 CHEVROLET SILVERADO
178,000 MILES • 5.3L • V8 • 4WD • AUTOMATIC
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PSBOWLER
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My truck blows hot air initially until the engine gets up to temperature and then goes to cool air. I can shut the truck off and restart and get hot air again. I do hear clicking under the dash leading me to believe there is a malfunction with the blend door. As, there are four of these. Is the temperature control the one under the dash or am I looking at trying to get to one of the other three?

Thanks.
Aug 10, 2017 at 1:39 PM
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DOCFIXIT
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Automatic temperature controls? if yes see diagram for mode actuator.
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Apr 30, 2021 at 1:53 PM
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PSBOWLER
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Yes, automatic controls. I will give that one a try. Thanks.
Apr 30, 2021 at 1:53 PM
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STRAILER
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Here is another guide that can help

https://www.2carpros.com/articles/replace-blend-door-motor

Please let us know what happens.

Cheers, Ken
Apr 30, 2021 at 1:53 PM
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PSBOWLER
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Just an update and maybe issue is different. Yesterday I had the AC on and after about 5 minutes heat started to blow out of all vents, front and rear. Never had a problem with the AC, only heat. Did a HVAC recalibration procedure on it this morning and no change. The mode actuator is the one that changes from floor to vent to defrost, correct? Or am I looking at wrong ones. I see a tech bulletin from GM that has a software update for this type of issue, or could the actual control module be malfunctions. I just don't want to tear apart the entire dash if actuators are not causing the problem.
Apr 30, 2021 at 1:53 PM
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STRAILER
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Yep the control module can be going out we have not replaced to many of these but it is possible.
Apr 30, 2021 at 1:53 PM