I tried connecting a new blower motor to an external 12V power source and the motor didn't work? From what I read that motor works on ground potential versus voltage regulation.

I'm trying to figure out if the new motor is bad or if I have other issues trying to get the motor to work in the car, i.e. bad regulator or bad cliimate control unit. Any advice?

I just took my motor out this weekend, like yours it wasn't working.
applied 12V to it and nothing happened, found a broken wire on one
of the brushes soldered it back applied 12V and it ran........Norm

I got the motor to work on the external source. thanks.