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Technical 6 Volt heater fan on 12 volt

Discussion in 'The Hokey Ass Message Board' started by Sporty45, Oct 19, 2020.

  1. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Will my 6 volt heater fan work on 12 volt? Or do I need one of those runtz reducers? This is on my 47 Olds
     
  2. poco
    Joined: Feb 9, 2009
    Posts: 400

    poco
    Member
    from oklahoma

    yes you need a runtz
     
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  3. The one on my '50 Buick works. Runs real fast.

    Ben
     
    Last edited: Oct 20, 2020
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  4. proartguy
    Joined: Apr 13, 2009
    Posts: 452

    proartguy
    Member
    from Sparks, NV

    I believe a Runtz is intended for low amperage like instruments. Heaters draw pretty good amps. I like to use a Volt-a-drop for heaters, they are made in different amperages.
     
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  5. F&J
    Joined: Apr 5, 2007
    Posts: 13,217

    F&J
    Member

    Runtz is for low milliamp draw, like gauges, it won't work on blower motors.

    Next possible thing that may be mentioned is a vintage underdash rheostat heater switch with 3 speeds. That won't work very well at all, as on HI, the rheostat will still get hot. On Medium speed even hotter, and on Low speed where it be most of the time, the switch will get so hot that it melts the colored insulation on crimp connectors. Leave it on low too long, and it may even ignite the plastic.

    I run an earlier vintage Olds heater with stock main motor and a mini motor for the defroster, both are 6v. Mine is my primary year round car, so I'm posting "heavy use" facts. I ended up using a vintage, very large (huge) ceramic resistor specifically made for such conversions, made maybe in the late 50s. That is the only thing that allows the underdash rheostat switch to not overheat on any speed.

    Best permanent solution, if you have only one blower motor, NAPA sells a generic barrel shaped 12v heater motor with 1/4" shaft that is the correct diameter for most vintage heaters, somebody listed the NAPA number on here in the past.
     
  6. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Where can you get them. I couldn't find anything with a google search
     
  7. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Can I use the stock heater switch to run it, or will I need to use a 12 volt heater switch?
     
  8. BigChief
    Joined: Jan 14, 2003
    Posts: 2,079

    BigChief
    Member

    Do a search for "runtz voltage reducer".

    Sent from my SM-G950U using The H.A.M.B. mobile app
     
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  9. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Thanks, but I was asking about the Volt-a-drop
     
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  10. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

  11. Bob Lowry
    Joined: Jan 19, 2020
    Posts: 218

    Bob Lowry


    Yep, for my '54 3100 Chevy truck, I used a VDO 12v motor available at O'Reilly's for $29. I believe the part number was VDO354. You may have to trim the 2 mounting stems, but not a big deal. Shaft size is correct. Same motor that Chev's of the 40's sells for $60 plus shipping! Bob
     
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  12. F&J
    Joined: Apr 5, 2007
    Posts: 13,217

    F&J
    Member

    that says 4 amp max or to run more in series.


    I see this one below that is rated 10 amps, 50 watts continuous use, same price. PM Crazy Steve for an educated opinion on watts/amps needed.
    https://www.ebay.com/itm/12-Volt-to...758294?hash=item27f9dd5bd6:g:WV4AAOSwQJhUjOWk


    Yes, your stock Olds switch should be the multi-speed rheostat type, and will work fine with a 12v motor


    This is definitely worth looking at for motor OD size comparison IMO. One important thing I forgot to say about using an old 6 v motor is that they often have worn bronze bushings that will squeal badly in winter temps when first turned on. Oil works, but not for very long. Make sure you know what rotation your old motor runs, and make sure the new one is the same.
     
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  13. heh heh
    You can sling the windings right off the armature if you don't keep the 6V motor speed within reason.
    I warned my friend...
    !!!! :)

    Sent from my SM-G981V using The H.A.M.B. mobile app
     
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  14. 62SY4
    Joined: Oct 30, 2009
    Posts: 86

    62SY4
    Member
    from Irwin, Pa

    I can't say for certain in this exact case, but my experience is a lot of the times there is a 12v motor that will fit the same bolt pattern as the existing motor assuming like most contemporary blower motors the two through bolts retain the motor to the housing, then it's a matter of insuring correct rotation, shaft dimensions and number of speeds. You needs to find a parts house that still has paper catalogs and find the "picture" book
     
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  15. Bob Lowry
    Joined: Jan 19, 2020
    Posts: 218

    Bob Lowry

    Last edited: Oct 19, 2020
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  16. wulf powis
    Joined: Jun 19, 2017
    Posts: 44

    wulf powis
    Member

    on the pre fifty fords I have found its easier to change out the motors to 12 volt, most of the motors with 1/4 shaft are interchangeable with slight mods. The motors usually run 30 to 40 dollars. such as this one
    https://apartswarehouse.com/Product/Show/1649
     
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  17. The best solution is a 12V motor. Trying to use a resistor puts a high heat source in the vehicle, never a good idea. If you choose that route, I'd recommend that it be installed where cooling is available, either in the engine compartment or inside the heater plenum where the fan blows air over it when in use. This is what the OEMs do for most multispeed fan motors.

    The other issue is choosing a ohms value that gives the desired reduction. For best results, you need to know what the existing current draw is. It should also be noted that doing this will increase the current draw on the circuit which may overload the existing switch, and you'll need a higher watt rating resistor.

    If you use a 12V motor, your existing switch should be adequate for the current draw. If it has built-in resistors, the fan speeds will probably vary from stock.
     
  18. Budget36
    Joined: Nov 29, 2014
    Posts: 4,208

    Budget36
    Member

    I did long time ago, put a ballast resistor in series with the switch, and left it on low...didn't seem like it spun too fast, but that ballast resistor did warm up some.
     
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  19. sdluck
    Joined: Sep 19, 2006
    Posts: 2,524

    sdluck
    Member

    My buddies 1954 belair heater blower has been running on 12v for 12 plus years.It was a ragtop,we always had the top down.
     
    Last edited: Oct 20, 2020
  20. Using a regular old ceramic voltage reducer on mine. Works just fine.
     
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  21. big duece
    Joined: Jul 28, 2008
    Posts: 6,016

    big duece
    Member
    from kansas

  22. I have to agree with those that suggest finding a 12 volt motor that will fit. I've done that quite a few times and never had a problem getting one that is very close in size to original. One less thing to have to go back and fix properly later on when you could be enjoying the ride. ;)
     
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  23. G-son
    Joined: Dec 19, 2012
    Posts: 664

    G-son
    Member
    from Sweden

    "Voltage reducers" to give 6V... Bloody liars.

    Many of these are simply a resistor to put in series. Yes, this will reduce the voltage, but by how much depends on the current draw. At high current the voltage will be reduced a lot, at low current barely at all. So, when the fan is supposed to start the motor draws LOTS of current it will get a very low voltage, perhaps not even enough to start, it it's running at high speed the current draw may be low and the voltage reduction not enough.

    Using resistors to reduce voltage is a relatively bad idea, UNLESS the current draw is quite stable. For electric motors it is not, especially not when they have multiple speeds to choose between.

    What you want in cases like that is a voltage REGULATOR, electronics that actively regulate the voltage. Not traditional, we didn't have that when the declaration of independence was written, blah blah blah. We have them today and they are the proper solution to get a stable, lower voltage.
    Beware, several of those resistors sold to reduce 12 to 6V seems to be called regulators despite only being a resistor.

    But, as others have said. Changing to a 12V motor is the best solution. Keeps the installation as simple as possible.
     
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  24. jim snow
    Joined: Feb 16, 2007
    Posts: 1,110

    jim snow
    Member

    As others have said the best option is a 12 volt motor. I have just done this on the coupe. It works the balls. Snowman
     
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  25. hotrod37
    Joined: Aug 8, 2006
    Posts: 112

    hotrod37
    Member
    from Indiana

    I have a NAPA P/N for a 12 V heater motor that matches some 6 V motors (please check yours).
    P/N is 6551063.
     
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  26. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Thanks guys. Looks like a 12 volt motor would be the wisest move on my part. I'll have to take mine apart and do some measuring before ordering one though, gotta make sure! :cool:
     
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  27. Automotive Stud
    Joined: Sep 26, 2004
    Posts: 4,123

    Automotive Stud
    Member

    I ran my '47 with some kind of reducer, only got about a year out of it before the motor burned up. I wound up putting a 12v motor in it and was done with it. After that I've just put 12v motors in everything.
     
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  28. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Well the converter isn't going to do me any good anyway. Just tested both fan motors I have and neither one works!
     
  29. Sporty45
    Joined: Jun 1, 2015
    Posts: 845

    Sporty45
    Member
    from NH Boonies

    Well now we have another issue. My blower motor is a double shaft design, and all the ones I've seen listed in this thread are single output shaft. The rest of the dimensions on them are fine. Anyone have an idea on a double shaft model with similar dimensions?
     
  30. Budget36
    Joined: Nov 29, 2014
    Posts: 4,208

    Budget36
    Member

    Do you have a pic and measurements? I’ve a double shaft motor I used from a 82 ? I think Chevy PU. The old one may still be around to compare
     

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