I have no rear heat blowing out of the rear roof heat vents. Any ideas?

 

There's a valve at the rear blower unit that controls the flow of coolant through the rear system. It it's stuck closed, you will get air blowing, but no heat. There can be other causes, but the valve is a starting point of things to check.

 

Thanks for the reply. Where is that unit located?

 

The auxiliary (rear) HVAC unit is located under the passenger side trim panel over the rear wheel. Remove the trim panel. Looking at the assembly, you will see the blower motor near the rear of the unit. Just in front of the blower motor and attached with screws to the ducting is the auxiliary temperature actuator. It has a wiring harness that plugs into a recepticle just in front of and next to the blower motor. It's this actuator that Ithink you should check.

 

I got it off, turned the **** by hand and got heat. Trouble is, places like RockAuto.com claim I need part #640100 (according to GM for a 05 Tahoe) but says confirm the pin configuration first. It is different than mine. 640100 pin configuration looks like (.... )but Part # 640101 has a configuration of (.. ...) which is the same as mine and otherwise looks identical. They said I should check with a dealer. What do you think? Thanks,
John

 

Does anyone know if the rear HVAC unit is located in the same location (passenger side trim panel over the wheel) on a 2006 Tahoe as well? My dad's Tahoe is having the same problem as described here as well.

 

Correction, I mean a 2005?

 

Mine is a 2005 Z71. And it is under the passenger side rear tirewell panel. If you turn the rear fan on high you can hear it and there is an output vent there.

 

Excellent - Thank you! I'll take a look and see what I can find.