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Air condition issues

763 Views 2 Replies 2 Participants Last post by  stevewaclo
I've got an 03 GMC Sierra 2500HD that has some AC issues. The heater will only kick in if the temperature is at max, 90. otherwise it actually blows cold air.
few things to note:
the ac blender works; it switches between all modes as needed. the actuator doors also work, had 2 that were bad and I replaced them.I verified that they all move as needed. I did the calibration several times to make sure that's not the issue. I flushed the heating cold that's under the dash also. Water pump works; got hot going in, warm coming out.
it has the digital AC control type; also I used 2 separate units to make sure i didn't have a bad one.. they both do the same thing.
fuses are good...
Any ideas?

Thank you in advance.
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Hey guys; so after posting this, i was on another site that mentioned the temperature control sensor right above the drivers head. I thought that was on OnStar speaker. It isn't that's the temperature sensor. It made buzzing noise a few months ago so I unplugged it, thinking it was interfering with the radio. Ended up that was the issue. Hope this helps someone.

Thank you
Good catch and thanks for following up!

You’re not the first to discover a google can sometimes provide better results than our on site search function.

I’ve never noticed that sensor and will lay eyeballs upon it next visit to my truck.
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