My daughter is coming tomorrow with "no heater" problems with her 1997 Pontiac Sunfire. I replaced the thermostat a few weeks ago because of overheating. Everything seemed fine at the time but it was summer and I didn't try the heater. She says the fan switch is working, but no heat. The Haynes book says to check the heater control valve, but does not show a picture or say where it is located. Can someone give me a head start and tell me where to start looking for it? Thanks, Joe

I dont believe our cavalier cars ever had heater control valves, I know the old dodge shadows & Caravans did way back in 80' to earily 90's, My guess would be youre heater core is plugged Needs replacing, Or vaccum hose from youre heater control broke or popped off.

Thanks Rich. The Haynes book says "heater control valve", but I suppose that could mean the vacuum line that controls the flapper in the heater box. I will check when she brings the car tomorrow. Joe