2000 Grand Prix Heater Problem

[Lawenforcer]

Hello All,
Well it seems that when one thing goes wrong a bunch goes wrong, lol...Anyway, my heater will blow colder air and then blow heat out for awhile. It doesn't seem no particular time when it does it. It does seem like the heat works better when I get out on the open road. Blower seems to work fine. Which leads me to this. I have been watching my temp gauge and it has been all over the place. It shouldn't fluctuate nearly as much as it is, I am not sure if it is a thermostat or what. I am not sure what either of these problems are and where I should start on fixing. Not sure if the two problems are related either. Any and all help is greatly appreciated, it is starting to get a lot colder out....Thanks

[Fivefingerdeathpunch]

You could try a coolant flush, including doing the heat core to get anything out. Then toss in a new stock 195º thermostat and bleed the cooling system.

If the problem is still there, you might have a blend door problem.

[rperry435]

Sounds like a clogged heater core. Unhook both sides of the core from the engine. Blow out the gunk... most likely dexcool sludge. I used my mini shop vac to do mine just as a preventative measure when my motor was out a few weeks back. thermostat might be a good thing to replace because they are cheap.. perhaps time for a flush if you still have Dex cool. Just my thoughts.

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[Sven the Sexman]

Sounds like you have air in the cooling system. You probably have a leak. Either LIM gaskets or coolant elbows.

[rperry435]

Lol I was going to say if those don't fount blend door hut u beat me five finger lol

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[Lawenforcer]

I am starting to wonder if it might be the blender door possibly but not sure. I was having problem with the AC also and never got it checked out. It would blow out colder air out of the passenger side vents than the drivers side. I am just starting to get confused about all this AC/Heating problems...but I have to get it figured out. Something I got to have is heat, lol...