VCCA Home Forums TECHNICAL - GENERAL Electrical - 12 volt Wiring the heater on a 53

I'm in the process of converting my 53 210 to 12 volts. I purchased THIS voltage reducer to drop it back to 6 volts for the heater motor. My concern is there are a hot and ground wire for both input and output. I believe the heater has only a hot wire and grounds to the body. Would I wire both of this converter's ground wires to the body then connect the converter's input hot to the incoming 12v feed and the converter's output 6v wire to the heater motor? I can think of no other way to do it but thought I'd ask first.

Hi Tiny,

That is a nice package for a solid state transformer. I like the idea to use this rather than resistors to drop the voltage to an acceptable level. That is always tricky with a heater motor because there are already resistors in the speed control circuit.

I agree with your plan for wiring. Obviously the unit does not ground either side of the transformer function through the housing. That really adds flexibility for multiple applications.

The wiring diagram on the back makes sense to me. In the pictures the labels on the wires are confusing. I suggest that you might want to connect the ground side for the 6 volt output to a different location closer to the heater motor than the ground side of the 12 volt input. I know that might sound a little odd but that will minimize the chance for any voltage back-feed within the unit itself. Connecting the grounds to a common point could do that.

Based on what I see, the "In" red goes to battery 12 volt +, the "In" black goes to battery -. The "Out" yellow wire goes to the heater 6 volt hot wire, the "Out" black wire goes to the other heater wire. I would not rely on using the body/chassis for the ground (return) path.

Jim, so the heater doesn't ground to the body? It has hot and ground wires to it? If so that will simplify it. I've not visually inspected the motor yet. I assumed it was like my 38 with just one wire.

I also assumed that the fan motor was grounded through its mounting to the chassis. The heater was still a dealer installed accessory in 1953 so the fan is not in the wiring diagram for the car.

If it is a 2 wire set-up then I agree with Jim's approach.

I know this will be a real pain but you might consider insulating the fan motor from the chassis. Then connect the transformer output ground wire to the case of the motor.

We did something similar many years ago to install a negative ground radio in a positive ground car.

I agree with Rusty's suggestion of isolating the fan motor from the chassis. My reasoning is that the power adapter description does not tell us if the two black wires are at the same potential (ground), or whether the power adapter housing, which has holes for you to mount it to the body, is part of the circuit.

I am not familiar with the unit in question but to connect the in - it will be easier to use a good connection to the body. The out - will be controlled by how the fan motor is setup will need to determine if the fan is 2 or single speed, if it is a single speed with 1 wire or 2 speed with 2 wires it will ground through the body and the voltage converter will need to be connected the same. If it is a single speed with 2 wires 1 will be + and other -.
A lot of modern fans are multi speed designed to have constant power to the unit and switch the ground which is the opposite to earlier designs so carefully test which you have 1st.
Tony

Thanks everyone.

Way not just use the fan on low speed only that should drop in down enough, did that on a Studebaker for a friend and it worked ok.

Low speed on the fan leaves a bit to be desired in cool weather. I already have the transformer and it fails to an open circuit if overloaded then resets when it cools so nothing should burn up. I checked the heater motor draw with an analog 30 amp ammeter and the needle barely moved when I turned the fan on so the 10 amp capacity should be plenty. If the transformer fails to perform adequately I'll probably put a 12v motor on it but I'd rather keep it easily convertible back to stock if a future owner (read my son) desires to do so.

On the 1949-1952 heaer the blower motor does not run in the low position and the novement of the car fprces air through the heater. If I remember correctly the 1953 and 1954 operated in that manner also.