Reversing a 12 volt 2 speed motor.

I'm converting an old art deco heater from 6 volt to 12 volt. The motor I acquired is a 2 speed ccw rotation 3 wire set up ( 1 ground / 2 power leads ). I didn't know the rotation until I powered it up. Problem being is I need it to be a cw rotation for the set up I have. I can't put the fan blade on backwards due to a lack of space ( hits the heater core ) and I've tried to reverse the ground and power leads and it still rotates ccw. Any help is appreciated.

 

If I remember my basic DC motor theory correctly the leads to the brushes (rotor) need to be reversed in order to change the polarity of the magnetic field in the rotor. The leads may be very difficult to get to even with the motor taken apart.

 

You might consider using a Balkamp single speed reversible (two wire) 12V motor from NAPA, like the #655-1022 I'm using on a '40s Ford heater. A simple reversing toggle switch changes the direction for heat or defrost, and an OE or aftermarket multiple resistor switch will change the speeds.

 

Thanks for the help. Wiring is one thing , this on the other hand is beyond me.

 

If the brush holder is made into the end cap and is a bolt on affair, you may be able to take the screws out and rotate the end 180 and make it change directions. I use to run into this on pump motors on some of the rebuilts I replaced in forklifts. These were single speed motors though. HTH, Dennis D

 

Bolting the fan backward will not change the direction of air flow. It will be less efficient it is kind of like turning a nut over it still screws on the same way. You might look for a fan that's pitched the other way.

 

This is the answer.... Most 12V DC motors are 'timed' for best results in just one direction and reversing them reduces power/rpm and increases brush wear. A reversible motor will have 'neutral' timing and will work better.

 

So it looks like there's two sets of windings and two leads to each brush. Would it be possible to cut one of the leads to the brushes and make it a single speed motor? I'm thinking then I could reverse it as long as I manage to cut the lead to the low speed windings. Just a thought , really have no clue if this is possible.

 

I do have a single speed reverseable motor on the way. If all else fails I'll make that do.