GM Service Manual Online
For 1990-2009 cars only

When replacing an air temperature, mode, recirculation actuator or the HVAC control assembly, the following calibration process needs to be performed:

Important: Do not adjust any controls on the HVAC control assembly during self-calibration. If interrupted, improper HVAC performance will result.

  1. Turn ON the ignition with the engine OFF.
  2. Turn the Temperature dial all the way to the right.
  3. Turn the blower control dial all the way to the right.
  4. Turn the mode position dial all the way to the left.
  5. Simultaneously press and hold the A/C and Defrost buttons until the LED's start to flash.
  6. Once the LED's stop flashing, calibration is complete.