Mazda Blower Motor Resistor

Not that I've heard. I understand they use PWM on model railways, their tiny motors use permanent magnets.

The only problem I've ever had on a model locomotive using PWM power was the rapid variations in torque causing the plastic, and marginally specified, drive gears to fail. For better motor control, some controllers even sense the back EMF of the motor during the off portion of the wave to adjust the speed.

PWM is also used by the electric model car racers and fliers, apparently without problwms apart from a bit of RFI, which is easily suppressed.

I stand corrected. I guess these rare earth magnets are tougher than the old Hornby things we had when I was a kid, which would demagnetise on their own...

Andy

Even they weren't adversely affected by PWM controllers. They were/ are just crappy magnets.

use it on model aircraft too. It works.

And that's a much more energy-efficient method of reducing the fan speed.

Not Graham-Farish by any chance?

SteveW

No, Egger Bahn, IIRC. A very small, very light, OO9 0-4-0 locomotive. I could hear the armature vibrating, it was that light.

I note that Google shows many many people wanting to know how to fix this problem. Basically the resistor part corrodes and breaks. The new part costs, in my case, 25% of the value of the car. And this is the third time the same resistor has failed. No it's not a faulty blower motor, it's the resistor that fails because its design is faulty.

I intend to replace the faulty (and badly designed) resistor with external wire wound resistors, which are very cheap and reliable. I am having trouble finding the wattage of the blower motor. My theory is that the new resistors should be able to dissipate the total wattage of the motor. I could try to measure the current taken by the motor, but I can't because the resistor is open circuit, remember?

Mazda in their infinite wisdom have stated that the blower motor is 12 volts but have not bothered to state the wattage. Does anyone know the wattage? There does not appear to be a model number on the motor. Why not?

Somebody who may be correct has stated that the four resistors are

I assume that when the blower is on full speed there is no resistance in the circuit. The resistors are presumably added in the circuit to slow the motor down. I'm not sure in what order each resistor is added.

Any information that anyone has will be gratefully read by the many people Googling for Mazda blower resistor.

Use your ammeter in parallel with the open circuit resistor to get the full speed current, then use V*I for the power. You'll need a 30 amp range for safety and to measure the initial surge current at starting.

Some Ford and VW vehicles have it. Switch to intermittent and off again. Switch it back on when the screen needs wiping again and it remembers the interval.

MBQ

You've solved your own quandary there - assuming the blower still works at max speed then you can measure the current draw in that state.

Mathew