Midas Cars Forum - www.midascarsforum.com

benofbrum wrote:I used one of those Rover resistor units and mounted it on the side of the battery box with the plastic mounting uppermost and open on the sides. When I went to the classic car show at the Bath and West showground, the demister was on all the way down from Birmingham on the middle or low speed with no problems. Remember, even on the lower settings, most of the power will still be dissipated in the heater motor and at full power, no current goes through the resistors.

benofbrum wrote:The heater motor is only a single speed unit. The speed reductions are obtained via the resistor pack. You will also need the appropriate switch, which has to carry the full motor current at max speed. On Citroen BX's which I have owned in the past, the fan speed was controlled by a rheostat (variable resistor) which varied the control current to a power transistor which then fed the motor. These control units became quite rare.

fozzza wrote:

benofbrum wrote:
On the Car builder solutions website they do sell a fan speed conversion switch but it costs £30 and it is a rotary switchI will use off/on/on heater rocker switch repositioned on the dash and the rover resistor and wire it accordingly to give me about half speed and bypass it to give me full speed.

Geoff Butcher wrote:

fozzza wrote:

benofbrum wrote:
On the Car builder solutions website they do sell a fan speed conversion switch but it costs £30 and it is a rotary switchI will use off/on/on heater rocker switch repositioned on the dash and the rover resistor and wire it accordingly to give me about half speed and bypass it to give me full speed.

Just like a Morris Minor! I've got one of those if anyone wants it. (Switch, that is, not a Minor)