HVAC Actuator Recalibration Procedure For GM Trucks and SUVs

The topic of how to perform the actuator recalibration procedure on Chevrolet , GMC and Cadillac Trucks and SUVs has become an ever increasing topic of discussion.

For manual systems it does not matter where the a/c controls are set but if you feel the need to do something, turn the blower switch on (I prefer speed 3) and set the temperature sliders about .5″ to .75″ from full cold.

For auto systems, press the auto button, with the key on.

Turn the ignition off.

Remove the HVAC/ECAS , 10 amp fuse in the underhood fuse box* or disconnect the battery for one minute.

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*Fuse locations can vary from year to year and between different models. Hopefully I will be able to build a list for this.

Install the HVAC fuse or reconnect the battery.

Start the engine. On systems with auto a/c controls the controls will default to 74 degrees F when the ignition is turned back on.

DO NOT TOUCH the a/c controls.

Let the engine run for 1-2 minutes.
Turn the ignition off for at least 10 seconds but no more than 30 seconds.
Restart the engine and then test the a/c controls.

301 discussions on “HVAC Actuator Recalibration Procedure For GM Trucks and SUVs”

  1. Pulled both HVAC fuses (under hood and drivers side dash). Got it to blow cool air for passenger side and rear. Drivers side still blows hot air. (It is close to 100 degrees today, so i dont expect super cold air.)
    Drew

  2. First check to make sure both the evaporator tubes at the firewall, under the hood are cold and equal in temperature. If not you have a refrigerant issue. If so remove the hush panel under the passenger side of the dash. There is an actuator on the bottom of the HVAC box just above the transmission floor hump. It is then driver’s temperature door actuator. Look to see if the shaft is turning. Both by command and after a recalibration. If it moves to the cold position but returns to heat quickly there are two common possibilities. Poor connection at the passenger side junction block or a faulty actuator.

  3. ok, did it 3 more times. Same outcome. I am able to switch between vents. Floor, dash, defrost. Both sides are blowing hot air. I do not have a scan tool, other than the one that they would use if I went to Autozone or somewhere similar. Not sure if that one will do it. I also have rear climate control, which is controlled by knobs over the rear view mirror. I have that set to 74 degrees, auto fan, auto direction (feet/head/both). I did not touch these controls after starting the process. The rear seems to blow cold (or cooler) than when the front starts blowing heat. I wouldnt call it cold, more like lukewarm. I am also able to switch the rear controls to feet, head, or both. So at this point, I have directional control over both the front and rear HVAC, just unable to get it cooling for longer than a few seconds after the recalibration.
    -Drew

  4. I will attempt the recalibration again. I was careful not to touch any controls once the procedure started. I did not notice if all vents were blowing hot air, just the drivers side ones. I will take notice of this when I recalibrate again, and will report back. Ill check to see if I can switch between vents. Thanks
    -Drew

  5. I would attempt the recalibration several times and make sure you do not interrupt the procedure. Did control over the air flow positions get corrected after your first recalibration? Are both sides blowing hot air or just one? Do you have access to a scan tool to read HVAC codes?

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