[redrail1]

I have 2004 yukon with rear heat it just blows cold, found the coolant lines they are hot on both sides in and out where they go in I think the rear core what should I look for now thanks

 

[redrail1]

anyone idea's

 

[pokrmnylt1]

Sounds like an undercharged system.

 

[MPL-tk]

Have seen a couple come through the dealer that needed the rear hvac control head and an actuator. I wasn't the one who diag. it but I'll look into it.

 

[MPL-tk]

PSB # 06-01-39-015A sayes to replace the rear HVAC control module with an updated one with new calibration for being unable to control rear temp. The control module commands the actuator out of its limits and then is stuck. May have to replace actuator aswell.