Blower motor polarity

[PCshedman]

Am fitting an old Smiths heater (due to matrix failure of Maverick one) which is a blower/matrix complete unit. like on the old mini. There are two white wires come out of it and no stamped-on indication of polarity. It seems to work connected either way round.Is there any way I can check polarity as think those old vehicles were positive earth?

 

[solarman216]

connect it and whichever way round blows hardest that is the correct way, Rick

 

[PCshedman]

yes, thats what I guessed but didn't want to cause damage. This due to shape of fan blades only?

 

[rayf3262]

you might try earthing the frame of the heater and seeing if you have a choice of 2 speeds!! worth checking out, because if it is intended to be wired that way with 12v across the 2 white wires it will be running slower than Mr Smith intended....

 

[ssteve]

wont damage anything, will just suck instead of blowing, most likely neg earth

ssteve

 

[ssteve]

just checked in my "69 to 88" mini w/shop manuel all motors are two wires connected to terminals

ssteve

 

[PCshedman]

So its just a case of connecting both ways to see which works best?

 

[ssteve]

you got it!!

ssteve

 

[PCshedman]

Thanks to all.Much easier option than changing the Maverick matrix!

 

[harlowmaverick]

pictures?

can you post some pictures of where you have fitted it andhow you have connected the piping up please, just for future reference for others

 

[rustic]

If DC motors have permanent magnets, like scalectric cars, then reversing the wires will reverse the direction of the motor.

If the motor has a field winding ie a coil in place of the permanent magnets then the direction of the motor will be the same irrespective which one is connected to ground.
As per earlier thread check that nothing is earthed to the chassis of the motor housing first.

On the matter of changing the motor direction on a field wound motor, you would need to re-wire the motor, by either reversing the wires on the brushes, OR the wires on the field coil.:thumbs

That's why electric drills work on ac, they have field coils and they reverse the voltage 50 times per second (50 Hz), and the motor always goes in the same direction.:thumbs

 

[ssteve]

If DC motors have permanent magnets, like scalectric cars, then reversing the wires will reverse the direction of the motor.

If the motor has a field winding ie a coil in place of the permanent magnets then the direction of the motor will be the same irrespective which one is connected to ground.
As per earlier thread check that nothing is earthed to the chassis of the motor housing first.

On the matter of changing the motor direction on a field wound motor, you would need to re-wire the motor, by either reversing the wires on the brushes, OR the wires on the field coil.:thumbs

That's why electric drills work on ac, they have field coils and they reverse the voltage 50 times per second (50 Hz), and the motor always goes in the same direction.:thumbs

in other words connect wires to terminals and see what happens!!

ssteve

 

[(RIP) PLANK]

you might try earthing the frame of the heater and seeing if you have a choice of 2 speeds!! worth checking out, because if it is intended to be wired that way with 12v across the 2 white wires it will be running slower than Mr Smith intended....

good point, so body could be negative, and two wires for different speeds, would you power one or the other, or one and the other for different speeds i wonder.

 

[Peasgood]

good point, so body could be negative, and two wires for different speeds, would you power one or the other, or one and the other for different speeds i wonder.

That would be my guess.
On my Mk1 Capri it's that way, one of the wires goes to a resistor to get the slow speed.

 

[(RIP) PLANK]

That would be my guess.
On my Mk1 Capri it's that way, one of the wires goes to a resistor to get the slow speed.

so one wire may need a ballast resistor to do the slower speed, should be easy enough to do though

 

[ssteve]

just connect it up ,the tensione is killing me!!

ssteve