2004 Grand Prix No Heat

[Rodgerwilco]

First off the details:
2004 Grand Prix GT2
3800 III engine
67k miles

The problem:
Very little or no heat coming out of the vents, even at normal operating temp. The first thing I did was to replace the thermostat. No good. Today I did a flush and fill and had nice heat coming out of the vents. But since it was nice outside I turned the heat down, and when I turned it back up... no heat again. The hoses to the heater are hot on the top one and cold for the lower, so it doesn't seem to be circulating, however after I did the fill it was fine, with both of them hot. The question I have is there some kind of heater valve or solenoid that could be sticking and not allowing the water to flow? I have no problems with it overheating or anything like that and the car runs great except for this weird problem. Could it be electrical having to do with the temp knob etc? I'm at a loss on this one.

[00GTP4ME]

Welcome to AF!

What temp thermostat did you put in?

When you say that you get no heat, is it that the air coming out is cold(er), or that there is little/no air coming out at all?

How does the engine temp act? Is everything normal there? Could it be a water pump issue?

Don't worry, the other guys on here are more helpful than I am.

[Rodgerwilco]

I put in the standard one 195 degrees I believe.

No warm air or just very slightly warm (not hot like it should be) coming out of the vents, but plenty of air, so the fan is working fine.

Engine temp is fine, warms up like it should, not overheating.

[rickisrad]

check for any leaks, coolant elbow, intake, etc.... Replace the radiator cap, if it is bad it will prevent proper pressurization of the system. Make sure the system is bled properly ( at the bleeder valve). Also make sure your air actuator is working properly, the easiest way to check this is to turn the fan on low and move the temperature control knob back and forth listening for it to move freely.

[tblake]

A member had this issue a little while ago with his 05 I believe. What he did was unhooked both hoses from the motor that go to the heater core, and he ran water through them and flushed the heater core out. Last I heard he had heat again. Then he flushed the whole coolant system again and replaced it with 50/50 prestone dex-cool and distilled water.

I would try that. I'd be willing to bet your heater core has a blockage if the top hose is hot and bottom hose is cold.

[Rodgerwilco]

Originally Posted by tblake

A member had this issue a little while ago with his 05 I believe. What he did was unhooked both hoses from the motor that go to the heater core, and he ran water through them and flushed the heater core out. Last I heard he had heat again. Then he flushed the whole coolant system again and replaced it with 50/50 prestone dex-cool and distilled water.

I would try that. I'd be willing to bet your heater core has a blockage if the top hose is hot and bottom hose is cold.

Ok, thanks. I will give that a try just as soon as we get rid of the 8 inches of snow we got over the last 2 days. :-)

To Rickisrad - The actuator is working BTW and seems to be moving freely.

[tblake]

Originally Posted by Rodgerwilco

Ok, thanks. I will give that a try just as soon as we get rid of the 8 inches of snow we got over the last 2 days. :-)

Yuck! We got hammered in MN, snowed for 3 days in a row over christmas, totalling a couple feet. But since then, not really anything measurable.

[Rodgerwilco]

Hey guys... finally after about a month of bad weather and procrastination, I fixed the no heat problem.

Fix was to disconect both heater hoses and back flush the heater core. At first it didn't want to let water flow, which indicated that there was a definite blockage. Then with a little bit more pressure from the garden hose it suddenly started to flow. When I reversed the flow to the direction it normaly works, I got several large chunks of what looked like rock out the end of the heater hose. That was the blockage, I guess we can thank the Dex-cool for the build up.

Anyway, thanks for the suggestions and the help. Problem fixed.

[valente]

Originally Posted by Rodgerwilco

Hey guys... finally after about a month of bad weather and procrastination, I fixed the no heat problem.

Fix was to disconect both heater hoses and back flush the heater core. At first it didn't want to let water flow, which indicated that there was a definite blockage. Then with a little bit more pressure from the garden hose it suddenly started to flow. When I reversed the flow to the direction it normaly works, I got several large chunks of what looked like rock out the end of the heater hose. That was the blockage, I guess we can thank the Dex-cool for the build up.

Anyway, thanks for the suggestions and the help. Problem fixed.

same problem i had,and its exacly what i did and what the Dex-cool(mud)looked like.glad you got it