Non-Hybrid Saturn Aura models may display the warning message "A/C off for Engine Protection" on the instrument panel. This may be accompanied by illumination of the check engine light and the temperature gauge reading cold at all times. This is a feature of the engine that is activated by the power control module when it detects the engine warming up too slowly. The OBD trouble code P0128 may also be stored. 

The cause is simply a worn out thermostat that stays open at all times, preventing the engine from reaching the proper operating temperature. 

Replacement of the thermostat will correct the issue.