2003 Buick Park Avenue. 3.8 V6 engine.
Question: The heater doesn't always put out heat.. I replaced the Thermostat. The old one appeared o.k. , but I replaced it anyway...Example Backed out of garage to go to a class luncheon, drove 2 miles to pick up my lady.. I let the car run ,went in & got her ,came out & drove to the luncheon approx 1 mile... Shut the car off, went to luncheon ,came out 2 hours later & started car .. Within 5 min the heat was pouring out.. This has happened several times.. The Dealer can't find anything wrong... Can You HELP me ??
Answer: If you have gotten the car up to operating temperature and the heat is on, it should blow warm air. Different driving circumstances can lead to different ways the HVAC system acts. Outside temperature, driving style, cold start up, etc, all will differ in how long it takes to produce heat in the car. If the car is hot and you have no heat, you could have a few possible causes for that. The thermostat could be sticking, even if it is new. You could have an electrical problem with the HVAC control head, or the temperature door actuator.
If either of those have a problem, it could blow cold air when you want it on heat. You may also have a partially clogged heater core, radiator, or both. You may want to try a coolant flush for starters and possibly another thermostat. That would be the easiest thing to do first.