[Mgs] heater motor wiring

[Barney Gaylord]

Steve,

-- First things first.  If there is no instruction sheet with the new 
motor telling you how to handle the incorrect wire terminal(s), then 
call the vendor immediatery to report the faulty part.  There should 
be two black wires with bullet connectors. Please let me (or us) know 
the response.  Can you send me a picture of the new motor and the wire ends?

Heater motor harness wires in MGA should be Black, and Green/browN 
(GN), not Green.  See here: http://mgaguru.com/mgtech/electric/circ_f1.htm

All MGA and early MGB heater motors are not polarity sensitive.  They 
will run the same direction even if you switch the wires, which is 
why both wires on the motor are Black.  Difference between MGA and 
MGB is opposite rotation (different part number for the motor).  To 
reverse the rotation requires opening the motor housing to swap wires 
on the field coils (a minor soldering exercise).  Put your new motor 
an a battery to be sure it turns the right direction.

Later production MGB heater motor is polarity sensitive.  Switching 
wires makes it run backward.  These may bo permanent magnet motors 
(possibly more powerful for higher speed).  These motors will have 
color coded wires.

I think MGB GT V8 heater motor is shorter (about 1-inch), needed to 
clear the cylinder head on the V8 engine.  Got one of those from V.B. 
some years ago (one size fits all) and sent it back.  Pretty sure 
that one is a permanent magnet motor.  MGB 1975-1980 heater motor has 
three wires (possibly two speed?).

Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com


At 08:06 PM 1/4/2011 -0500, Steve Petrosky wrote:
>I purchased a new heater motor for my mga 1500 (moss # 363-040) and 
>need help connecting to the wiring harness.
>
>The harness has two wires, one green one black but the motor only 
>has one new style connection, maybe a 1/4" spade type. how should 
>this be hooked up.  Is the spade connector for the green wire? and I 
>can attach the black wire to the housing for a ground?
>....