2007 Heat Blowing Cold – Actuator help

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#12749 Closed 2007 Chevrolet 2500HD Duramax Diesel public

Greetings Sparky. I have a 2007 2500HD that is having issues with the cold to heat knob. I have narrowed the issue down to the actuator itself or the door itself. My question that I can’t seem to find the answer to is with the manual cold/heat (non dual climate systems) where is the actuator that controls my system? Is it up under the dash on top of the heater box as is the passenger blend actuator on the dual climate systems I have seen videos on?

I have tried the reset procedure (via pulling the batteries) and have been able to hear all of the actuators cycling. I am assuming it’s the blend door actuator or door itself being hung up as if I adjust the knob from cool to heat with the ignition in the run position And the truck quiet – with each step I can hear the actuator cycle and adjust until right before I get to the exact middle of cold to heat then the actuator makes a noise that is best described as bogging down. Kinda a whirrrrrrrrrrr to stop sound. Any thoughts? Thank you in advance.


If you have single zone manual a/c controls the temperature door actuator is under the HVAC box on the passenger side of the vehicle just above the transmission hump in the floor pan. If you have dual zone manual controls the driver’s temperature door actuator is located in the same position mentioned earlier. The passenger side temperature door actuator is located on top of the HVAC case to the right of the radio area. Once you have accessed the actuator you are concerned with it is just a matter of looking to see if the actuator shaft is actually moving when commanded. Also keep in mind that checking the engine coolant level is a must do step anytime there is no heat. The heater core in you truck is the highest spot in the cooling system and the first to empty if the coolant level drops.

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