Shoot, there is more information I already knew that I should have posted, which would have saved this... The fan actually only comes on when the temperature gets about 3/4 the way up the temp. guage. For a while I thought it was broken or a signal was getting to it somehow, but it did eventually come on. About the car not burning as much fuel at highway speed... that does make sense! I never really thought of that. The only thing is, could the car REALLY be designed that way? I mean, from what I understand, the thermostat should NOT open until the engine is very warm, and until it does open, the coolant should just keep circulating inside the engine (and through the heater core) until its gets quite warm, when the thermostat should open. So to test this operation, I tried driving with the heater set to cold (just to make sure) and the fan to OFF. It still will not allow the temp. gauge to get above the cold level. Is there really enough cold air at 110km/h (65mph?) to cool the engine completely, offsetting all the explosions happening at 2000-3000 RPM? I am no scientist, but that seems odd to think that could be possible... its not like it is -40 outside afterall... Actually, the temperature only have to drop to about -5 to
-10 celcius (25-15 fahrenheit) for this problem to occur. If the temperature is above zero, the temp. guage will read warm and I can get more heat..
Is there ANY possible was that some lines could be hooked up wrong that would allow the engine to bypass the thermostat and let some coolant get through to the radiator? I tried tracing all lines and it really seems impossible, but I am at a loss here! There has to be something wrong... surely Chrysler couldn't have designed such a poor cooling/heating system...