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. I thought it might be that year model. What happens is that the control head will fit several years of applications. The newer year models use an evaporator core temperature sensor. The control head comes pre programmed for the newer vehicles. Yours does not have this sensor and therefore has no way to report back that the evaporator core is too cold. The system ices up and air flow stops. Installing the old program into the new control panel is the only way to get it to work correctly.

      1. Many times this will correct the condition. It works really well when a previous recalibration process was interrupted inadvertently. When other work is done on the vehicle that required that the battery be disconnected a recalibration will automatically begin when the battery is reconnected and the ignition is switched on. If any HVAC control button is moved the recalibration is interrupted and the actuators will be stuck where they were positioned at the time of the interruption. It is very important to make sure the recalibration procedure is allowed to complete any time that the battery has been disconnected. If an actuator has a real problem sometimes performing the recalibration will coax it back to working for a while.

        1. I’m having this problem with my 2005 buick rainier and I took fuse out then replaced after bout 15 sec then turn key on and the ext temperature rest was like 138degrees and I let key stay on on position for bout min and half and then started my truck and the front vents still not working and external temperature stayed on 138 and dropped to 117…the dash is not making any clicking noise all i hear is the blower…what’s my next step

  4. It all started when my driver side vents would go crazy and blow out hot air even though the passenger side was cold. I now know this was all due to a battery failure and replacement. At the same time I learned how to calibrate the actuator I decided to change out my HVAC control module because it looked terrible from all the paint that had flaked off. Shortly after replacing the module I had a new problem where I would lose air volume but I could still hear the fan blowing. I tried calibrating a few more times with failure every time. I then removed the hush panel and checked all actuators and they were all working fine. I then opened the hood to investigate more when I found the entire HVAC system was froze up. I then came to a conclusion that my system is freezing the coils and that is why I was getting no air. A simple search on the web and sure enough a new control module has to be flashed by the dealer to work properly. Took it to the dealer and $100 later and it is all fixed. A label on the module telling me it must be flashed would have been helpful. I hope this helps others with the same problem I have encountered.

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