my car is over heating i have to run heater to keep temp down what are the possible problems?

Could be thermostat, clogged radiator, failing water pump, or low coolant, but most probably the head gasket is blown. This is a common problem with the '90s Grand Prix cars. Suggest having a mechanic pressure test the cooling system to tell you if there are internal leaks.

I would defnitely have the head gasket checked, i had the same problem for the longest time. Check your antifreeze for oil in too, thats a good sign its the gasket.

I have the same problem and I know it’s not the heads because I have to replace the engine and the new engine does the same thing as the old one! The cooling fans won’t come on except if I turn on the AC but even then they don’t kick on hi. on my 2007 Grand Prix there is just one sensor that tells the computer what temp it is at and to turn on the fans. I am starting to think it my computer. I have a now temp sender and thermostat and water pump and flushed the cooling system and still the same thing!

I have a 2006 Grand Prix and my car also has this issue. Only when I idol during the heat does the temp gauge go up. I can have the ac on or off and it does the same thing. I do not have this problem during the winter. I have also had to have my water pump replaced at just under 70,000 miles. I have also had issues with it leaking anti freeze in the past that had to be fixed.

I have a 2002 Pontiac grand prix with 402,078 miles on it. No heat or air. I can have the gas pedal on the floor board but it won't go past 40 to 70 mph. The red TEMP light comes on and the temperature gauge says it's 260 or higher. Is it the thermostat?