Cannot Get Cabin Temperature Off Heat

[bluenova8177]

I have a '00 Silverado 1500 extd cab, 4.8l, 4L60e trans with 270,000+ miles. The problem I am having is that after using the a/c, defrost or heating (once truck is at operating temp), I cannot get the heat to stop. Turning the temp adjust knob has no effect, it stays at full heat. If I turn the a/c on it's still hot. Only after letting the truck completely cool off, will the a/c actually blow cold again. The compressor works fine, the inside temp will drop to less than 40 degrees so I dont think it is a charge or compressor issue. I have searched the site and cannot find a similar topic addressing this problem. Is the temp control vacuum controlled? is the blend door also vacuum or is it electrical? I have been dealing with this problem now for a couple of years and I've decided its time to take care of it once and for all.

 

Thank you in advance for advice, tips or comments you might have to offer.

 

Blue

[mkimber]

Mine did the same thing. Get a new blend door actuator motor and that'll fix it. It's an electrical unit mounted under the dash by the cabin filters. Real easy to install and costs about $75.

[bluenova8177]

Mine did the same thing. Get a new blend door actuator motor and that'll fix it. It's an electrical unit mounted under the dash by the cabin filters. Real easy to install and costs about $75.

 

 

Thanks for the info, will be changing it out soon

[jimbrown1]

Mine did the same thing. Get a new blend door actuator motor and that'll fix it. It's an electrical unit mounted under the dash by the cabin filters. Real easy to install and costs about $75.

 

Same thing happened to my 2005 Sierra on the way home from Dallas to Houston. Wife's side (passenger) stayed on hot the whole time. It was the actuator.