Heater Motors

[55 Fargo]

Hi all, have done aquite a bit of reading on this , did the searches, looked at my old posts, and still am not 100% sure how I might proceed.

My heater box for the truck is 6 volt, and it does not like a diet of 12 volts, that I have, the heater switch gets red hot on either speed real quick, a lot of amperage draw.

I have the box on the bench, motor is out, it looks very similar to the motor blueskies Pete used, with the exception of the mounting studs are on the opposite side of the motor case.

I could also order a 50 watt voltage dropper, my concern with these is, will they get super hot, and will they cause a fire, neither of which I want.

I have no qualms about using 1 of these dvices, as long as it works and is safe.

My other option is a 12 volt motor, whcih I will try and find on Monday.

My 3rd concern is the beat up heater control switch, should I replace it with modern, for safety sake. I am alos tempted to change the headlight switch to to something modern and safer.

I also found a voltage regulator on the back of a modern cluster, is that for reducing voltage to the gauges?? thanx Fred

[Oldguy48]

I think finding a 12V motor would be the best method. A voltage dropping resistor will work, but it will get HOT. I suppose you could mount one on a heat sink of some sort, but to drop the voltage to the heater motor to 6V, it will have to dissipate the same amount of energy that the heater motor is consuming. If the heater motor draws 12 amperes (not sure if this is what the heater motor actually draws), then 12 amperes will also be flowing thru the voltage dropping resistor. Power equals voltage multiplied by current, so 6 volts x 12 amperes equals 72 watts of power. You'd probably want a 100 watt resistor (and in this case would require a 0.5 ohm resistor), which is fairly large, and you would have to mount it where the high temperature wouldn't be a problem. The resistor ohms value would have to be determined by the actual current that the heater motor consumed. Not very efficient.

As far as the headlight switch is concerned, you might consider using a relay, so that the headlight switch will have to handle a very low current, and the relay contacts will handle the higher current draw of the headlamps. The 12 volt relays I utilized needed about .070 amperes to energize the relay, but the relay contacts were rated for 40 amperes. Hope this helps you out.

Wayne

Edited March 12, 2012 by Oldguy48

[55 Fargo]

I think finding a 12V motor would be the best method. A voltage dropping resistor will work, but it will get HOT. I suppose you could mount one on a heat sink of some sort, but to drop the voltage to the heater motor to 6V, it will have to dissipate the same amount of energy that the heater motor is consuming. If the heater motor draws 12 amperes (not sure if this is what the heater motor actually draws), then 12 amperes will also be flowing thru the voltage dropping resistor. Power equals voltage multiplied by current, so 6 volts x 12 amperes equals 72 watts of power. You'd probably want a 100 watt resistor (and in this case would require a 0.5 ohm resistor), which is fairly large, and you would have to mount it where the high temperature wouldn't be a problem. The resistor ohms value would have to be determined by the actual current that the heater motor consumed. Not very efficient.

As far as the headlight switch is concerned, you might consider using a relay, so that the headlight switch will have to handle a very low current, and the relay contacts will handle the higher current draw of the headlamps. The 12 volt relays I utilized needed about .070 amperes to energize the relay, but the relay contacts were rated for 40 amperes. Hope this helps you out.

Wayne

Thanx Wayne, going to try and source a 12 volt motor for this heater. The light swich should havea realy, but at least with the 12 volts it should have 1/2 the amp draw as it would have with the 6 volt bulbs it was built for, plus the 30 amp stud circuit breaker is there too. I have found in my parts a voltage regulator for the gauges, this will help with my heat and gas gauge too...