2001 Buick Century - Is it the thermostat or something else?

Question

The heater took FOREVER to come on at the end of winter last year. (Sometimes would go back off.) Tried to de-fogg the windshield last night and got no heat. Drove home fighting the fog and the heat never came on at all. Any advice is appreciated.

Answer 1

Yes, it sound like the thermostat is stuck open. Another symptom is a decrease in mileage.

Answer 2

1 of 2 probable causes there.. thermostat stuck open, or heater core plugged. See if the heater hoses feel hot after you run it a bit. if they aren't and the rad cap isn't hot, then thermostat, if they and rad cap ARE hot, then heater core is plugged. I'm betting on the thermostat though.