Expert: autohelp - 8/24/2009

Question
After my husband drives the car for a while the cold ac blows warm air then the car signals that it is  overheating and also says ac compressor is off.As long as we dont turn the ac on the car is drivable .the thermostat was recently serviced it has antifreeze new radiator and did i mention the heater does not work as well. ANY ANSWERS WOULD BE GREATLY APPRECIATED THANKS.

Answer
When the engine temperature gets to the overheat range the computer AUTOMATICALLY shuts OFF the A/C compressor.

This particular year vehicle and engine has a long history of blown head gaskets due to stripped out head bolts which allows combustion chamber pressure into the coolant chambers thus restricting the flow of engine coolant.

You need to have a back pressure test performed on each cylinder where a constant amount of air pressure is put into each cylinder via the spark plug hole and you look for bubbles in the radiator cap opening. If you see bubbles, You have a blown head gasket due to stripped out head bolt threads in the engine block.