1950 heater motor problems
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1950 heater motor problems
I have just got into checking out my heater to put back in my truck, and after checking the heater core to see if it was good, I thought I would see if the motor would turn ok. Got out my battery charger, made sure it was on six volts, etc. and found my motor would not turn on low and turns quite slow on "high". This was the same in the defrost mode. If I switched to 12 volt I couls get both speeds, although alittle fast. Did these old six volt systems actually put out a little more than six volts? I will be running a 12 volt neg ground system and thought I could step down the volts to run the old system. Will this work? Or does anyone know of a 12 volt motor that will fit?
Thanks, Alan
Thanks, Alan
Fleet Mechanic
Joined: Jun 2004
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From: Minnesota
The old 6 volt systems actually put out about 7.5 volts. You could run the motor on 12 volts until it dies then have it rebuilt for 12 volts. You could also get a potentiometer and have better adjustements.
Fleet Mechanic
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From: clinton,tn
heater switch
i saw your post and went out to the garage and got the part number off of the box of the heater control i got from napa. i used it on my 6 volt heater after i changed it over to 12 volts. it is a echlin #hc6050. so far it works great. it will go down to a slow speed and up to full speed. but dont run it full too long. the motor is still a 6 volt . the system puts out 7.2 volts on the 6 volt system at full charge. hope this helps you.
Last edited by 1949f1; Dec 4, 2004 at 07:41 PM.
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Thanks guys, I think there is nothing wrong with my motor, Terry, you may be right about the amperage as I was using a trickle charger to try this.
Vern, when using the rheostat, did you have to do anything with the wiring? as the old system was positive ground?
Alan
Vern, when using the rheostat, did you have to do anything with the wiring? as the old system was positive ground?
Alan
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Fleet Mechanic
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From: Minnesota
Someone double check this math
If I were doing this to my truck and was worried about burning up the motor. I would put a resistor in the main power line from the battery and drop the voltage to 7.2 volts. I have not got that far so I do not have the exact numbers to figure out what the resistor would be. You can figure it out by
- Checking the voltage of your system while it is running most 12 volt systems actually run about 14.7 volts.
- You know that you want 7.2 volts at the fan motor so you need to drop 7.5 volts accross the new resistor added inline.
- Find out what the current draw of your motor is at 7.2 volts maybe someone here with a stock system can give you that number. My book says a 1950 and 1951 Ford truck is 10 amps so I am going to go with that.
- Resistance equals voltage 7.2 volts divided by current 10amps so the motor windings should have about 0.72 ohm resistance. You can check that easily with a multimeter.
- Current is a constant across the entire circuit so 7.5 volts divided by 10 amps = 0.75 ohms. So you need a 0.75 ohm resitor.
- Power or Watts = voltage x current so 7.5 volts x 10 amps = 75 watts. If my book is correct you need a 0.75 ohm resistor that can handle 75 watts. That is a big resistor and allot of heat.
- I would get the windings rewound for 12 volts. That extra resistor would be a big drain on the electrical system that is being wasted in heat.
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50 merc- I took my 48 heater motor to a bone yard and they had many 12v ones to choose from on a shelf. I wish i could remember what mine came out of for you, but it was easy to find a 12v match. Terry
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From: Littleton, New Hampshire
Originally Posted by 50 Merc
Vern, when using the rheostat, did you have to do anything with the wiring? as the old system was positive ground?
Alan
Alan
The cars I ran with the 6V motor on 12V were 6V negative ground (Mopars), so it was not necessary to make any changes in the wiring.
Vern
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