2004 Pontiac Grand Prix No heat when idle

ALPHADOGL13

MEMBER
2004 PONTIAC GRAND PRIX

Heater problem
2004 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic 110k miles

My 2004 Pontiac Grand Prix GT2 recently (about 2 weeks) began blowing cool air when the heat is on and idling or sitting at a stop light. When the car is on the express way or in constant motion it blows out heat. What could be the problem?

6 Replies

JDL

MECHANIC
16,098 POSTS

Welcome to the forum, no difference in air flow? It's just a temp issue? Does the engine reach operating temp? Are the heater hoses hot, when the problem occurs? You might need to have the heater core flushed. The flow through the heater core probably slows down at idle because the water pump slows down.

SPONSORED LINKS

Was this

answer

helpful?

Yes

Monday, January 4th, 2010 AT 10:10 AM

ALPHADOGL13

MEMBER
4 POSTS

Thanks for the welcome. No difference in airflow at all. It is just a temp issue. The engine does reach operating temp but I haven't checked the heater hoses yet. Having the heater core flushed sounds like a good idea but I just had the coolant system flushed recently? I thought it might be the thermostat?

Was this

answer

helpful?

Yes

Monday, January 4th, 2010 AT 10:41 AM

JDL

MECHANIC
16,098 POSTS

If the problem only happens at idle and the engine reaches operating temp, I don't think the thermostat is the problem. Replacing it shouldn't hurt anything, but, I don't see it.

Was this

answer

helpful?

Yes

Monday, January 4th, 2010 AT 12:28 PM

ALPHADOGL13

MEMBER
4 POSTS

Thanks! I will do both and see what happens. I'll have the hoses checked as well. I'll let you know the outcome as I'm going to my mechanic today.

Was this

answer

helpful?

Yes

Monday, January 4th, 2010 AT 12:50 PM

JUSTASIAM313

MEMBER
1 POST

Have you found out wat was going on with your grand prix. Im having the same problem and it is starting to tick me off because I dont do much highway driving there for its always cold in my car.