This light comes on briefly while starting the vehicle.
If it does not, have the vehicle serviced by the dealer/retailer. If the system is working normally the indicator light goes off.
Notice: Driving with the engine coolant temperature warning light on could cause the vehicle to overheat. See Engine Overheating.
The vehicle's engine could be damaged, and it might not be covered by the vehicle warranty. Never drive with the engine coolant temperature warning light on.
The engine coolant temperature warning light comes on when the engine has overheated.
If this happens pull over and turn off the engine as soon as possible. See Engine Overheating for more information.
Chevrolet Cobalt Service & Repair Manual. Air Conditioning System Leak, Inspection
A visual inspection must always
be performed to confirm the presence of aftermarket components, potential
collision damage, or areas of concern. With the oils used for R12 systems,
leak areas often collected much dirt and would build up sometimes large
displays of road grime. ...