Pontiac Repair: grand am over heating, intake manifold gasket, crank case

Question
my 96 grand am, v6, auto,intermitantly over heats sometimes after going a mile sometimes after several miles. The overheating of the engine coinsides with the heater blowing cool air instead of hot. When heater starts blowing hot again, engine cools right down.

Answer
Hey Hugh:

The car is low on coolant. there is a leak in  the system somewhere either external where it's leaking onto the ground "outside of the engine" or internal where the coolant is leaking into the engine crank case or it's being burnt in the cylinders. The most likley cause is a lower intake manifold gasket leaking. VERY common on these cars. next would be a water pump and the last thing to look for would be a head gasket leaking. If you have been driving this like this for a while it WILL DO DAMAGE to the engine so do not continue to drive it untill you get it looked at. Good luck :)