I have been reading all the threads addressing the problems with the heaters/ac units in these cars. Well, the thermostat in my car, 944S2, does not seem to work the same way as the one in my past 951. When it is cold out and I want to set the thermo to a warmer temp, the heater will come on FULL heat until the right temp is achieved. That is fine, I guess, but then the heater swithes to allow the outside (COLD) air air into the car until it becomes very cold in the car and then the cycle continues. This is not the way that I remember the unit in my old 951 working. Is there something wrong with my heater valve, vaccuum, or rheostat? The thread about a week ago mentioned the heater valve, is this the problem?

 

Is the selonoid valve the culprit?