[Mgs] heater motor wiring

[Paul Hunt]

FWIW the '2 speed' heater fan consists of a single-speed motor with a 
dropper resistor inside the heater unit casing.  For the first speed the 
current goes via the resistor to the motor, for the second speed the 
resistor is bypassed.  The resistor is in the air flow for cooling (common 
in more modern cars).

The Parts Catalogue indicates the motor was changed for *all* cars when the 
V8 was introduced in Dec 72, certainly by that time they are polarity 
sensitive.

PaulH.

----- Original Message ----- 
> ...  MGB 1975-1980 heater motor has three wires (possibly two speed?).