Climate control not working properly?

One common problem with the climate control system on these vehicles is a faulty temperature sensor. If the sensor is malfunctioning, it may not provide the proper temperature reading to the control module it is possible that there could be a programming issue with the climate control system.

CALIBRATION PROCEDURE WITHOUT A SCAN TOOL
1. Turn OFF the ignition.
2. Remove the battery positive voltage circuit fuse of the Instrument Panel Control Module.

IMPORTANT: The module memory will not clear if the battery positive voltage circuit fuse is installed in less than 60 seconds.

3. Wait 60 seconds.
4. Install the fuse.

CALIBRATION PROCEDURE WITH A SCAN TOOL
Use the following steps to perform the calibration update:
1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, select Instrument Panel Module.
4. Select Special Functions.
5. Select Miscellaneous Test.
6. Select Recalibrate all Motors.
7. Select ON, wait 30 seconds.
8. All counts will display zero and slowly the scan tool will begin to show counts

To access the HVAC (heating, ventilation, and air conditioning) codes on a 2002 Cadillac Seville, you can use the following procedure:

Turn the ignition key to the "ON" position, but do not start the engine.
Press the "OFF" and "WARMER" buttons on the climate control panel at the same time and hold them for several seconds until the display begins to flash.
Release the "OFF" and "WARMER" buttons and the display will show the HVAC diagnostic mode.

Use the "AUTO" button to advance through the diagnostic codes, and the "HI" and "LO" buttons to cycle through the different data points within each code.
Write down any codes that are displayed, along with their associated data points.

Please let us know what you find.

It sounds like the HVAC controller needs to be replaced here are instructions on how to do the repair. Check out the images (Below). Please let us know if you need anything else to get the problem fixed.