Heater Fan Rotation?

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®
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Brad Gates
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Heater Fan Rotation?

Post by Brad Gates » Mon Aug 20, 2018 12:15 pm

Help,
I have a very early 6 volt hot water heater that mounts to the inside firewall on the drivers side of '46 CJ-2A. This is before the days of the Harrison Heater. It's been cleaned, painted and pressure checked and all is good. After powering up the motor I noticed that air is drawn "up" thru the heater core and pushed out the top of heater. Meaning that "hot" air is directed up under the dash. This seems counterproductive to how a heater should work!

Can anyone verify this observation? The heater has not been modified to my knowledge. And "NO" changing the wires does not reverse fan rotation.

Thanks for your help.

BRAD

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Re: Heater Fan Rotation?

Post by Steve Webb » Mon Aug 20, 2018 6:26 pm

I know bupkis about what it should do but does it look like the fan could be turned over so it will blow down? Possible during work it was assembled wrong.
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Re: Heater Fan Rotation?

Post by Bruce W » Mon Aug 20, 2018 7:16 pm

Steve Webb wrote:
Mon Aug 20, 2018 6:26 pm
I know bupkis about what it should do but does it look like the fan could be turned over so it will blow down? Possible during work it was assembled wrong.
A very common false assumption. Turning the fan blade over will not reverse the direction of flow. Now, turning the motor end-for-end would, but you would have to have a motor with enough shaft exposed on both ends to install the blade on either end. I'd bet that the motor has been replaced, and is wrong. Especially if it has two wires. I believe the originals only had one wire. BW

Edit to add: Your battery is installed, negative ground, correct? BW
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Brad Gates
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Re: Heater Fan Rotation?

Post by Brad Gates » Mon Aug 20, 2018 7:30 pm

You are correct, fan orientation on shaft makes no difference. It is a 2 wire motor. Electrics are 6 volt negative ground. Motor appears original as it fits very well in assembly. I might have literature showing this heater as accessory. Will check tonight. THANKS for feedback.

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Re: Heater Fan Rotation?

Post by YLG80 » Tue Aug 21, 2018 5:17 am

Just curious to understand why you cannot reverse the motor rotation by reversing the 6V DC wiring ?
Is there any reason?
Yves
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Brad Gates
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Re: Heater Fan Rotation?

Post by Brad Gates » Tue Aug 21, 2018 6:42 am

Gentlemen,
Found this bit of information in my Willys Maintenance Manual dated 9-11-45. Sounds like the fan directs air onto the drivers feet. So my motor is "reversed" or has been changed over the years. It just looks "too correct" to have been replaced. Curious if anyone has access to the installation instructions???
Only DC motors with permanent magnets can be reversed by changing polarity. A standard brushed DC motor needs the field polarity changed.
Keep digging ! THANKS
BRAD
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Re: Heater Fan Rotation?

Post by Wolfman » Tue Aug 21, 2018 7:25 am

What Brad said, Yves. When you reverse the input polarity to the motor, it reverses both the armature and field magnetic fields and the motor still turns the same direction. Same, same as with a starter.
You may have answered your own question, Brad. Either the motor is wrong or the fan blade is wrong for the application. Even thought they both fit.
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Re: Heater Fan Rotation?

Post by YLG80 » Tue Aug 21, 2018 8:39 am

So if if it's the type of motor shown in that topic, I would open it and see if I can modify the field wiring.
viewtopic.php?t=194753
It looks like that the motor casing can be opened

For the driver side, I've found a convenient heater : During the winter, I simply remove the brake cylinder cover inspection plate.
It heats up my feet very well :D !
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Re: Heater Fan Rotation?

Post by Wolfman » Tue Aug 21, 2018 11:42 am

A little more complicated than just moving a wire or two, Yves.
Has to do with the location of the brushes on the armature commutator. This determines where the field around the armature is located.
The magnetic field formed around field windings are fixed, but moving the location of the brushes on the armature moves the location of the magnetic field that forms around the armature. So, if you want to change the armature rotation, you have to move the brushes to an equal distance in relation to the field winding, in the opposite direction of shaft rotation, from their current location.
Need a different brush holder or at least, a major overhaul of the present one.

:D With your heater, I would not recommend driving through any mud puddles ! :lol:
Mike Wolford
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Re: Heater Fan Rotation?

Post by Brad Gates » Wed Aug 22, 2018 10:54 am

Gentlemen,

PROBLEM SOLVED!!! Too much delicate work to rebuild the fan motor as you indicated. Looked thru my pile of "too valuable to throw away" stuff and found a fan assembly with blade angle just opposite of the original. Air now blows down over drivers feet. About all this can do is make you feel cozy!! Not much air hitting the floor.
THANKS for all the input.

BRAD

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