Blend Door Actuator

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#14020 Closed 2004 Chevy Tahoe Z71 public

Hey Sparky –
I’ve got a problem with my HVAC panel blend door actuator (front driver’s side; the one that controls the air flow direction – defrost, front, and floor). After hearing a grinding noise coming from this actuator (OE), I removed it and replaced it with an aftermarket actuator (replaced the rear HVAC system actuators with the same parts before and they worked fine). After wiring the new actuator up, I performed the HVAC recalibration procedure by pulling and replacing the HVAC fuse in the exterior (under hood) fuse box and cycling the ignition to calibrate. Oddly, after I ran the recalibration procedure, the new actuator cycles through its range of motion and then returns to the floor position – and then does NOT respond to the HVAC controls from the head unit. Here’s what I’ve tried:

+ Tried the original part (the one that was grinding). Same thing – cycles all the way through, returns to the floor position, and then won’t respond to controls.
+ I’d recently replaced the HVAC head unit with an OE (AC Delco) head unit. Switched it out with the original head unit to see if the new one had been affected by the recalibration. No luck – same result as above.
+ Cleaned the pins on both the actuator and the wiring harness to see if there was any dirt that was interfering with the signal. No luck there either.
+ Performed the recalibration again, with both the external (under hood) and internal (below steering wheel) HVAC fuses. Have done the procedure several times. No luck.

The new actuator cycles through a complete range of motion every time I turn the ignition on, but after it returns to the floor position, it’s unresponsive to controls. I’m at a loss. About to take it in to the dealership, but wanted to see if you have any ideas first.
Thanks for the help!


Unfortunately I need to see some data information to give an accurate diagnosis. My best guess would  be that the either the interior or exterior temperature sensor is reading very cold and sending the system into the default heat position.

Thanks for the feedback. The actuator in question is the one that controls the panel position, not the temp. It’s defaulting to the defrost position. Is there something I can send you – data – that would help?


Do you have a scan tool that can communicate with the HVAC system?

I’ve got a BlueDriver plug. It’s throwing three HVAC codes. I’ve looked them all up along with the top reported fixes. They all say that the actuator should be replaced (already did that) and recalibrated (done that). Shall I send those codes to you?


You can but do you have access to live data stream with your tool?

Only thing is streams live is the fuel trim. Sounds like I need to take it to the dealership or a local mech to get better data?

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