Clicking under dash

PSBOWLER

MEMBER
2004 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
178,000 MILES

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.

5 Replies

DOCFIXIT

MECHANIC
18,828 POSTS

Automatic temperature controls? If yes see diagram for mode actuator.

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Friday, April 30th, 2021 AT 1:53 PM

PSBOWLER

MEMBER
5 POSTS

Yes, automatic controls. I will give that one a try. Thanks.

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Friday, April 30th, 2021 AT 1:53 PM

KEN L

MASTER CERTIFIED MECHANIC
42,884 POSTS

Here is another guide that can help

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

Please let us know what happens.

Cheers, Ken

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Friday, April 30th, 2021 AT 1:53 PM

PSBOWLER

MEMBER
5 POSTS

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.

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Friday, April 30th, 2021 AT 1:53 PM

KEN L