2004 Buick Park Avenue

Heater problem
2004 Buick Park Avenue 6 cyl Front Wheel Drive Automatic

2004 park avenue with climate control. Heater blows cold air. I have cleaned the cooling system and replaced the thermostat. After letting the car warm up, I noticed that the heater inlet hose was hot but the outlet hose was cold. Is there a shutoff or does the water circulate through the heater at all times? I'm not sure if the core is plugged or if it is a control problem.
Please help.
November 20, 2009.

Actually, your car has a blend door that opens and closes to allow heat to enter the vehicle. With the engine hot, running, and the heater on, both heater core hoses should be hot. I would start by flushing the heater core. Like you mentioned, it may be plugged.

Let me know what you find.