Quote:
Originally Posted by shimon340
Thanks Umski!
Potentiometer output signal is then the input to the smaller transistor here rather than a PWM? I can see it could be either option (potentiometer output or PWM) and indeed one or the other (or both system types could be the same signal) for if the car has climate control or not too.
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Glad to hear someone has found this useful
Bit of a blast from the past but my last fix still seems to be working - the only odd thing is that the speed control sometimes flip-flops from 'hi' to 'full' when on 'auto' so I can hear the relay clicking on and off - not sure what triggers this - probably a dicky ECC unit. However, related is your point about potentiometers - yes the speed is an input to the ECC but probably one of many going into a microcontroller first I imagine recalling the PCB behind the dash (made by Motorola I think) - this would also include the reading from the ambient temperature from the thermistor and vent position I guess - a bit like an ECU does...so back to the original question, I still believe that the speed is driven by a PWM signal from the control unit since it is using a transistor to control the speed rather than just dropping voltage across a resistor pack like on the earlier phase...keep us posted on your discoveries
