Hello, I wired my car from scratch when I built it but never hooked up the heater blower motor. I found an identical motor to the stock one but 12 volts. It runs great. In times of desperation, I've jumped the wire and used it, like when driving in 5°f. I was wondering if my stock 6 volt heater fan speed resistor (porcelain wrapped with wire?) would work on 12v? Thanks Sent from my iPhone using The H.A.M.B. mobile app
Are you still 6 volts?, if so, only potential down side is the blower would spin slower, if you converted to 12 volts, I'd be willing to bet the original switch will be just fine.
I've tried many stock 6v switches running 12v motors. They don't vary the speed & get way hotter than you'd want.
It should; the resistor doesn't care about voltage, only current. The 12V fan motor probably draws less than the stock 6V motor did, so it should work. But because it was designed with a 6V motor in mind, the fan speed reduction won't be the same. And it will get hot; the factories usually mounted these inside the heater plenum from the mid-50s up because the air circulation helped cool them.
Thanks guys. Hot doesn't seem good. Anything out there that it can be replaced with? Sent from my iPhone using H.A.M.B.
If you're trying to eliminate the heat issue, the easy answer is no. If you're into electronics, you could build a solid-state voltage reducer but the size/cost/complexity of it will be far more than a simple resistor. Just mount the resistor some place with adequate clearance from anything combustible and it'll be fine.
Or bypass it and have only one fan speed. My car forces air in anyway so no fan still means decent heat. Also My resister is part Of the levers/switch Sent from my iPhone using H.A.M.B.
Thing is, you can run your 6 volt heater motor off of 12 volts. Depending on your location and winter driving habits, it could last months or it could last years. But picking up a new 12 volt motor pretty cheap and not bad to replace. So buy it now or buy it later, up to you.
Well... There are some simple pulse width modulation circuits (PWM) that can control large currents with minimal heat loss. They rapidly turns the current on and off, typically >20 000 times per second (to avoid making noises you can hear). Letting the full 12V through for 50% of the time, and turning it off to give 0V for 50% off the time, makes an average of 6V, and simple devices like motors or light bulbs will work just like on ordinary "stable" 6V on that. Can't use it for complicated electronics like a radio though. A DIY-example. I'm sure there are many complete curcuits available to buy online, or you might just be able to cannibalize one out of a suitable cordless drill or something like that. http://www.instructables.com/id/12V-NE555-PWM-Controller/
Millions of cars and trucks came with multiple resistors. GM and Chrysler products for sure, from the 70s to the 90s. Any one would probably work but if it was me I would get one to match the motor. Is it from GM, Ford, Chrysler? If it is just a generic motor then get what you like. Use a suitable multi position switch. Look up the wiring diagram from anything that had that type resistor and switch. As Crazy Steve pointed out, the resistor is usually mounted in the heater plenum to keep it cool. Often you can get at them from under the hood.
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