One of the reasons Trasborg bought this particular truck in the first place was that somebody had equipped it with a heater. However, once he moved to SoCal he never bothered hooking it up. It looked like a cold front was coming in, so he rigged it up using the old manual choke cable and some bailing wire to get the hot/cold selector working. A simple switch wired in controls the blower motor. With no resistor or anything and just wiring the blower motor to 12V will give you the high speed setting only.