For 1990-2009 cars

The HVAC control module will not request compressor clutch engagement when the ambient air temperature display is less than 2°C (35°F). In order to inspect compressor clutch operation during cold weather conditions, the vehicle must be brought inside and the ambient air temperature display must be updated. To update the ambient air temperature display on the HVAC control module, perform the following procedure:

#### With out Scan Tool

1. Turn ON the ignition.
2. Simultaneously press the A/C and RECIRC switches.

#### With Scan Tool

1. Turn ON the ignition.
2. Use the Instant OAT Update procedure in the scan tool Special Functions.