wireing for replacement heater motor to 1940 switch

[Thomas Sargent]

I have a 1940 hot water heater for my 40 sedan, and want to convert it to 12volt. I have located a 12v universal motor from DC that looks very close to being correct dimensionally, but it has 5 wires coming out while the original 6v has only 4. the description for the replacement motor says it will run either way but how do I hook this up to my origional switch? The origional has 3 wires from the motor to the sw and one with a spade terminal on the end. the switch takes those three wires from the motor and there is a fourth wire that I think is the hot in. Help. IMG_7841.jpg

IMG_7838.jpg
Pix of switch and existing old 6v wireing

[19Fordy]

Tom: Do a search "How to wire a 1940 Ford heater" and info. like this appears.
https://www.fordbarn.com/forum/showt...40+ford+heater

[petehoovie]

Originally Posted by Thomas Sargent

I have a 1940 hot water heater for my 40 sedan, and want to convert it to 12volt. I have located a 12v universal motor from DC that looks very close to being correct dimensionally, but it has 5 wires coming out while the original 6v has only 4. the description for the replacement motor says it will run either way but how do I hook this up to my origional switch? The origional has 3 wires from the motor to the sw and one with a spade terminal on the end. the switch takes those three wires from the motor and there is a fourth wire that I think is the hot in. Help. Attachment 541660

Attachment 541661
Pix of switch and existing old 6v wireing

[ActionYobbo]

On my 12/6 conversion the dashboard and heater are still 6v while the engine and lights are 12v.
To me it’s the simplest way. Run a 12v battery with a 6v regulator to feed the dashboard. You might find your new motor Wont run off your old switch. You should have main power to the switch and the wires coming out are the motor speeds. The new motors might have main power direct to the motor and low voltage switching for speeds.

[TJ]

Isn't there a wiring diagram with the motor?

[kartrae7]

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You will have to reduce voltage to 6v. The resistors on switch for the speeds will get super hot run on 12.

[19Fordy]

Will this help?
https://www.fordbarn.com/forum/showthread.php?p=144357

I can't find a way to open this link that used to be easily accessable.
http://www.btc-bci.com/~billben/flathead.htm

[FortyNiner]

This may help.

[Thomas Sargent]

fantastic info, thank you very much. This is more than I had hoped for.
Tom