Hi.
Bought a radiator fan motor for a 2002 Mustang to vent a hot attic, fed by a solar panel.

Has 3 wire connector, probably a 2 speed, one is black.

Turning by hand, feels permanent magnet type with very soft detents. How to tell if it is brushed or not ?
If wired to reverse direction / polarity being brushless will it release the smoke ?

 

Many automotive motors are BLDC now , one way to detect is a brushed motor will generate DC when back fed,, a BLDC or 3ph comutation type will generate AC sine waves.
BTW, both types are PM now.

 

Perfect response, thanks. Turning by hand generates + or - depending rotation. Now I can install to suck from the attic and blow out.

 

Now all you need to do is discover which wire is the common for the two speeds. For a brush type DC motor for an automobile application, one terminal is the negative(common), one wire is HI speed, and one wire is the LOW speed.
It will be bad news if you connect the DC power between the high speed and low speed wires.

 

My two yen:
To prolong the fan’s lifespan, it would be worthwhile to have a simple temperature controller to select either high or low speed.

 

Good chance the BLK is common and BRN & BLUE Hi-Lo.

 

If spinning the motor generates a voltage then set it up with a fan blowing on the - um - fan. With it spinning at a constant rate measure voltages Black to Brown, Black to Blue, Brown to blue. Whichever gives you the higher voltage is likely the high speed. Undoubtedly you'll get reverse voltages when spinning the fan in the opposite direction. Most certainly if you're getting voltages I'd doubt if it's BLDC.

Found this:
https://www.americanmuscle.com/alls...n-13-inch-curved-blade-1350-cfm-all30074.html
About 2/5ths down there's a statement that says the fan is reversible by reversing the wires. I don't think BLDC fans can be reversed. I may be wrong.

 

. Most certainly if you're getting voltages I'd doubt if it's BLDC.

BLDC & PM 3ph AC both usually generate a 3 phase wave form,
A schematic I came across showed BLK=GND, RED and BLU = speeds

 

Installed. + to black (reversed) mounted inside attic exhausts towards outside. All fine. It is a plain brushed type.
No temperature control. Sunny = hot attic = fan runs from solar panel. Sunset = off. Winter = switched to shut off.