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View Full Version : Heater control knob - how does it work?



BenR
25-06-2007, 10:33 AM
I have the semi-automatic heating and AC. The heater temperature control knob baffles me - the action seems too light for it to be turning anything other than an electronic control so how does it work? It is unpredictable; sometimes a quarter turn makes it hot and sometimes you need over half to get any heat. Am I right in thinking that it's not linked directly to the water temperature but operates as a thermostat, controlling cabin temperature? When you sit in the car with engine off and ignition on you can hear what I guess must be servos behind the dash constantly adjusting something - possibly the heater setting as the cabin warms or cools?

A second part to the question would then be: presumably if you run the AC but with the heater turned up, the internal thermostat will try to adjust the heater controls to achieve a set cabin temp even with chilled dried air entering the matrix?