heater fan only runs on high speed?

There is a heat fusible link attached to the top of the heater resistor. Check that with a multimeter it is most probably blown. also Check the heater motor runs freely check the bottom bearing is not dry and lubricate if needed. the fusible links are available from Farnell but cannot be soldered on as soldering will most probably blow the link. with mine i used a couple of block connector segments, and yes i have just fixed mine

Dave the technician
June 2010

what make and model is it

bob k
March 2010

it is most likely the resistor pack. they are often found mounted to the same box as the motor..

jim
March 2010