Heater issue

[tsuintx]

Rear heat and AC are fine, so no issues there. AC is nice and cold in the front, but I get proper heat only if I turn the temp knob past 82 to full hot. If I just turn it to 82, it's not really warm at all, maybe just a tad warmer than usual.

I guess the easiest answer to most GMT800 heater issues is either clogged heater core or issues with the blend door, but somehow I don't think mine is either one of those since the heat works when put to full hot...

Could it be the ACC module, maybe?

 

[Xypher]

Does the temp gauge go to about the 210 mark? Mine wasn't, so I pulled the tubes off both sides of the heater core and blasted with a hose on both sides for a couple minutes. Makes a mess, but it's quick and fixed mine!

 

[tsuintx]

Yup. Temp goes to normal level and stays there.

 

[Red Rider]

Could be your blend door that is not opening/closing all the way to allow heat. Try calibrating the actuators first.

If that does not work, pull rear quarter trim panel and see if actuators actually moving. The heater core should be getting hot no matter what.

 

[tsuintx]

Tried the calibration, but to no avail. And while i was working in there, I realized the rear actually has the same issue.

Hoses going into the heater core are hot and I'm getting hot air in all the outlets as designed, but only when it's cranked all the way to the right. Hence, I don't think the issue is with the heater core or at least some of the actuators.

I'm guessing there is some kind of blend door to blend hot and cold air, right? Seems like that would be the issue. Just haven't found too much info about it yet. Everybody always seems to have the issue that the temp is different on driver and passenger side or then they don't have heat at all. And neither of those are my issues.

Meh... Time to do some more reading. There has to somebody who has had a similar issue.

 

[Red Rider]

tsuintx,

Look at my thread: http://www.tahoeyukonforum.com/forum/showthread.php?t=66001

It explains the calibration steps that worked for me in detail. I cleaned up the 4th post to make sure it was super clear and people would not have to read entire thread. There are certain steps you need to do in order to calibrate properly.

Rear actuator is the hot cold one. If all is working fine, you should see the blend doors moving to vary heat, and the one to adjust where the air is flowing to (feet or head).

Good luck.

 

[tsuintx]

Thanks, Red Rider! I actually had read through your thread before, but thought used another calibration method I found in some other thread.

Today I then finally tried your method and lomand behold!!! It seems to have solved my issue! Haven't taken the truck for a ride yet to see if everything works also while driving, but at least they seemed to work while parked on the driveway.

This actually has got to be the first easy/simple/cheap fix that has ever fixed any of the issues I've ever had with any of my cars and trucks. LOL!!!

Again, thanks Red Rider!!!

 

[Red Rider]

It is the beer at the end that makes the difference! Glad it worked. Let us know if it holds. If not, you may need to replace controller. Good luck.


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