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The heater internal fan wiring is as follows:
Brown wire: provides 12-volt positive power from the fuse panel to the fanmotor (protrudes from heater casing).
Black wire: connects power from the motor to the heater fan switch.
Yellow wire: provides an earth for the heater fan motor on high-speed.
Red wire: provides an earth for the heater motor on low speed (via the low-speed resistor).The heater switch connections to the black, yellowand red wires are riveted at the back of the switch(i.e. not easily disassembled). A small piece ofcardboard, cellotaped on, insulates the rivetedterminals from the heater casing.
To check for a “bad earth” on the heater, examine the following locations for any
rust, paint, grease or looseness:a) the slot-head self tapping screw/star washer from the heater earth point,inside the fan blade housing.b) the two
the two ½” bolts connecting the dash -mounting-brackets to the dash.d) The battery earth lead terminal (though if this is a bad earth, a bad heater isprobably the least of your