1999 GMC Sierra Vortec 5.3 Check engine light.
I Changed actuator motor for the a/c and heater door.
Question = I hear a whirring and then a click click sound in my dash. The temperature control
would change from cold to hot. I was told it was the actuator motor. I replaced it with a known
good one. I took the Hvac1 fuse out to reset the motor but it still doesn't work. I took the motor
off of the dash and moved the control knob from cold to heat but the motor didn't rotate. Also
while I had the fuse out the whirring and clicking noise did not sound. But when it is put back in
the sound comes back. Any help would be greatly appreciated.

Answer:
By what you are describing, it sounds like either the actuator you replaced was not the
temperature door actuator- since it did not move when you turned the knob(which is a bad idea
because if it did move while not installed, it would overextend and ruin the actuator) or the
temperature actuator is not the one making the noise.

There are several actuators on your truck. Can you describe exactly the location of the one you
replaced? Does it have dual zone heater / AC ?
VISITOR: It does not have dual controls. The one I replaced was underneath the kick panel right
above the transmission hump. It had one plug with about six contacts and it was held in by two
5.5 mm screws.

Answer: Can you give me the first 5 digits of the VIN # please. With everything installed and
connected, it still makes the noise? When it does, disconnect that actuator and see what
happens.

VISITOR: Ok the vin and I will give you the whole thing is XXXX. I disconnected the actuator and
still hear the noise. I turned the passenger airing off just to make sure its not that. The noise
sounds like it is coming from the area of the airbag switch.

Answer: OK. Then the temp door is not the problem. Sounds like the mode door motor. See
attached pictured. #7 temp motor, #9 mode motor- more towards drivers side of dash. A better
procedure to relearn the motor positions after repair is to disconnect battery for a few minutes,
then start truck and DO NOT touch any AC control for 2-3 minutes, then shut off truck for 10
seconds,then restart and try the controls.

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1999 GMC Sierra Noise In Dash After Replacing Vent Actuator