Question about Pontiac Grand Prix

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I have a 2000 pontiac grand prix GT-- I all of a sudden have nothing but lukewarm heat at best blowing. Also my car always runs at 210 but now doesnt get even close to that. We replaced the thermostat, had the radiator checked and cap replaced. The heatercore has been flushed and hoses checked all fine. My husband said it heats up when sitting, but as soon as I drive it, well the temp goes down. My husband has checked everything he could think of with the heating system. Can anyone offer any suggestions? Im one step away from taking it to the dealer. Which Im sure will cost me a bundle! Please help!

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There is an inlet and outlet rubber hose going to your heater core. At operating temp the 2 hoses should be the same hot temp, if not, swap them making the inlet the outlet vise/versa and see if it makes a difference. Run vehicle like that a few days and this will make sure the core is unplugged. If this does not work there is a thermal relay in the blower compartment that may be faulty. To get at that you pull out the fan blower under dash and it will be right next to it. You may need to access the mounting screws for it through the hood and air sytem filter. I will put my money on a plugged core, even though it was flushed!!

Posted on Nov 07, 2010

  • morgantattoo Nov 07, 2010

    Thank you for replying. I just called my Husband to read him this solution. He is so stubborn and keeps telling me that the hoses are both the same hot temp. But the thermal relay hasnt been checked as far as I know. Which we never wouldve thought of, Thanks again for your expertise! I will keep you posted. Hoping it will fix this issue!



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