1997 Buick Regal mileage: 51,000. I've been having trouble with my car overheating. The engine light ONLY comes on while using the heater/defrost (NOT when we use the A/C though). A year ago, I replaced the water pump and thermostat (and its housing). Now the Heater refuses to work all the time. It did start to work after adding coolant and water, but the car still overheated. Any suggestions?
Your radiator may be low on water causing it to overheat. Coolant may be lost through a blown head gasket or it could be that the radiator is plugged which causes overheating resulting in the lose of coolant.