"cold on drivers side and hot on the passenger ". This is the problem I have a few times during the cold weather. It has always fixed itself after a few restarts, so it's not a big enough problem to tear the dash apart.
Calibration Procedure
Use the following steps to perform the calibration update:
Turn OFF the ignition.
Remove the battery positive voltage circuit fuse of the HVAC Control Module.
Important: The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds.
Wait 60 seconds.
Install the fuse.
Wait 60 seconds before moving the HVAC controls.
(I'm not sure if the links below are still good)
The guy at dealership told me to remove the panel under steering wheel and i could get to actuators. They quoted me $150 to change it, that was part included.
http://ww.tbssowners.com/forums/showthread.php?t=79585
The actuator has a feedback circuit to the control head. What happens is that the sweep resistor in the actuator might lose contact once in a while. When that happens, the control head doesn't know where the door is in the case and will default it all the way to one side.
the Driver's Side Temp Actuator seemed to have died. The driver's side would stay at full HOT no matter what I changed the Auto Temp Control to...
I finally ordered the actuator (PN 89018676) and tore the lower dash apart yesterday after work. As soon as I looked up under the dash, there was the "faulty" part...with the wiring harness plug sitting next to it, NOT plugged in! So I plugged it back in and tested everything...what do you know, it worked perfectly!
I recall unplugging it to make access to the Mode Door Actuator a lot easier. And I proceeded to forget to plug it back in!
There is the mode actuator which changes the vents which the HVAC system is set to blow air our of.
Then there is a temp actuator for each side (driver & passenger) that adjusts the temp of the air coming from the vents on the respective side of the truck.
You changed the driver side temp actuator. That is the easy one to change.
HVAC Mode Door Actuator?
Whenever the battery is disconnected the HVAC unit will perform a recalibration of all doors. This causes the door motors to be moved full cycle and the mode door will stick some times. I now hook a jump box to the system before changing the battery in Trailblazers or Envoys to prevent a recalibration from occurring.
Sparky's Answers - 2003 GMC Envoy, No A/C Vent Control, B0263
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