My 2002 Suburban began only blowing hot air this winter regardless of what the temperature dial is set at, AC on or off, recirculate, etc. The rear seems to be working just fine but the front is always hot. I only have one temperature control for the front. I do not have dual temp controls. I thought it was the blend door actuator that is below the dash on the passenger side but after replacing it I still have the same issue. I could use some help trouble shooting.

 

After replacing that actuator, did you make the computer "learn" and initialize this? I had to when our 2005 Yukon was doing similar, and there's a specialized procedure to do this. I bought a Dorman actuator, not GM.

With the lower cover off, can you disconnect the harness to this actuator and then turn the actuator from one position to the other to try? I had mine disconnected and set to "AC" position for a year before I decided we should restore heat function.

 

Narrow down the problem. Manually test the temp door by applying 12V.
If it works then, then you need test the control panel, fuses, wires, connectors etc.

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It appears or seemed like the door was stuck however. After moving it around and doing the reset it still only blows hot air. I'm becoming very frustrated with it as spring is here and I dont want to have to take it to shop and spend out the nose. It has 275k miles but runs great except for this one problem. Any other ideas?

Thanks for the help this far. Its greatly appreciated

 

I gave you some ideas.

 

Sorry. I saw that and will try that next. I had limited time and patience with it today. I'll let you know what I find. I appreciate what you posted. Hopefully that will help me figure this thing out!

 

Disconnect harness to the actuator; do test drive with that manually moved to the different positions.