My standard series 3 heater has a coil thingy riveted to the heater radiator. I've seen them on heater blower as well. Can someone explain what it's for and how it wires up? I am trying to complete a refurb of the system. I've got two live wires one to the heater motor the other to this coil? What attaches to the other end of the coil? The blower motor is earthed to the cowling. Thanks

Other side of resistor should also go to motor. One feed to resistor gives slow speed second feed bypasses resistor for high feed casing of fan housing should be earthed.

Thanks for that. Makes sense now. I'll try it on Friday when next got time.