03 Tahoe heat works only at 90

93redzj

93redzj

Well-Known Member
Joined
Aug 29, 2005
Location
Albemarle
Tahoe has dual climate control, I’ve replaced the control unit used to adjust heat setting, actuator on passenger side under dash replaced last year, and I’m currently fighting the one under dash on driver side which controls where the air flows, through vents, floor, defrost.

The issue now is, the heat will only work when the temp is turned up all the way to 90. If you set it to 89, it alternates between warm/cool air. I’ve tried searching around and came across a fix with inside air temp sensor located above driver head in headliner, changed that and still not fixed.

Heat/AC works on both passenger and driver side, rear works too. Just the heat only blows consistently hot at 90, any other degree setting and it’ll get cool/cold for a few minutes then warm up, then repeat

Any suggestions?
 
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My guess would have been the temp sensor, but you've already changed it. I'm not sure if there's any way to see what the temp sensor is reporting? You could have gotten a bad one out of the box.

My wife's 2005 will switch from heat to air when the outside temp is very close to the set temperature. Does your outside temp on the mirror read correctly?
 
LBarr2002 said:
My guess would have been the temp sensor, but you've already changed it. I'm not sure if there's any way to see what the temp sensor is reporting? You could have gotten a bad one out of the box.

My wife's 2005 will switch from heat to air when the outside temp is very close to the set temperature. Does your outside temp on the mirror read correctly?
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As far as I know it does, but now that you mention it, the display in the rear view mirror that shows temp and direction, does “glitch” from time to time. But not often

I also never have it set to “auto” if that would make a difference in this case. I always have it on either heat or AC with a set temp
 
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