2001 Tahoe Heat Fixed
 

I had the same problem I seen posted concerning not being ableto change from hot to cold and always blowing hot. Well %99 will be the temperature blend door actuator. After reading several post was not able to find the exact location, seen some saying you have to pull the dash apart WRONG, others say thereare only 2 screws WRONG. The removal of the dash is required to get to the main selector actuator (heat,AC, etc), the one only having to remove 2 screws is the air flow direction actuator (vent, floor, defrost) located on the drivers side right above the gas pedal (sorta). The actual temperature blend actuator requires removing the plentum for the HVAC. All work is done from the passenger side. There are 3 hex heab screws to remove, 2 are readily noticable and the 3rd is located above the transmission hump right behind console. A little tricky to get to but can be done with patience. After removing plentum the actuator is right above the hump passenger side. Actuator is held with 2 screws.
Replace in reverse. DO NOT HAVE IGNITION ON and read instructions.
****When replacing the plentum heres a good tip. For the screw that tried your patience removing above the hump take your socket and lightly tape the screw to the socket to hold while you break your neck...

Does anyone know how to diagnose whether these problems are with the actuator or the controls? My blend door is not stuck, and I can see that the actuator works. Unfortunately, it eventually stops working and seems like it needs to be "reset" by my truck being turned off for a while. I just don't want to change the actuator and it end up being the controls. Maybe someone has a diagnosis methodology on these or knows that the actuators may fail intermittantly???