Well, Barney, the heater motors on both my MGBs exhibit significantly
different output volumes according to which way the supply and ground are
connected to the motor. I would not have realised this except that when I
got my V8 as a daily driver I noticed the heater output was significantly
less than that of my roadster. Wondering if the PO of the roadster had
fitted a high-output fan (it was *his* daily driver) I took both motors out
and found them identical but that they rotated in different directions.
Reversing the connections on the V8 brought it up to the same 'performance'.
Can't speak for how the MGA is wound or how it differs from the MGB, have
you tried reversing yours just to see what happens, regardless of theory
(tricky chap, theory)?
PaulH.
----- Original Message -----
From: Barney Gaylord <barneymg@ntsource.com>
To: <mgs@autox.team.net>
Sent: Wednesday, July 19, 2000 11:35 PM
Subject: Re: Heater motor
> At 03:03 PM 7/19/2000 -0400, someone wrote:
> >....
> > Before you go to the effort to replace the fan, check that its wires
are
> correctly connected. The motor is DC, so will run fine in either
direction.
> The fan works better in one direction. ....
>
> Well, I've heard this at least a hundred times now, and I can't stand it
> any more. My MGA heater motor is a series wound DC motor and runs in the
> same direction regardless of the input polarity. When I procured a
> replacement motor that ran in the opposite direction I had to open the
case
> and swap the wires on the field coils to make it run the other way. I
just
> went and checked one a minute ago just to be sure I wasn't suddenly in a
> totally different universe, and it definitely does NOT change direction of
> rotation when the input power polarity is switched, but continues to run
in
> the same direction.
>
> I was (and still am) under the imperssion that ALL standard MG heater
> motors are series wound DC motors. To change rotational direction with a
> change of polarity would require having permanent magnets in there
> somewhere. Would someone please explain to me what kind of heater motor
> they have in their MG that would reverse direction just by reversing the
> current?
>
> BarneyGaylord
> 1958 MGA with an attitude
> http://www.ntsource.com/~barneymg
>
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