GM Service Manual Online
For 1990-2009 cars only

Calibration of the electronic climate control (ECC) module occurs whenever B+ is removed and then restored to the ECC module. During this calibration process the ECC module will automatically command the temperature door to the full HEAT position and then to full COLD position. The ECC module records both positions and uses this data to determine temperature door settings based on customer selected temperature settings.

Important: Do not select or use the scan tool HVAC menu during the ECC module calibration period or the ECC module will not calibrate properly.

If the ECC module has been interrupted by scan tool operation the temperature door will become inoperative. If this should occur then:

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the scan tool from the data link connector (DLC).
  3. Remove the RADIO fuse for 10 seconds and then reinstall the fuse.
  4. Place the ignition switch in the RUN position and wait 40 seconds for the ECC module to initialize.