Originally Posted by
GVK.
Basically the heater control panel (the hot/cold temp control) is a potentiometer that sends a PWM (pulse,width,modulated) signal to the heater control valve which has a motor on one of the connections.
Depending on the postion of the control, the motor is open/closed to regulate the flow of coolant to the heater matrix.
This can simply be tested by connecting a bulb into the HCV connector, with the car running, in the middle position between hot/cold, the bulb will flash about once a second, and with it either hot or all the way cold it will either stay on, or be off.
Thank you!
That explains the delay in temperature change as well. And it means you have to have the heat on often in summer too, otherwise the matrix will get clogged up.
Oh well, even a car as smart as a Puma has to have one brain fart it seems. Or two, if you count the unfortunate tailgate showers
