i just got it back from the shop and the only thing they could find wrong with it is some vacuum lines that they fixed. They do not no what is wrong with it and have givin up on it. Once the car has warmed up enough and i put the heater on it works for about 8 seconds and slowly start to turn cold and is completely cold in 15 seconds total. I can cut it off and turn it back on in a couple of minutes and it will do the same. Has anyone ever heard of such a problem.