Blower motor question

[Vinsane]

Hi all, I'm sure this is a dumb question but here goes anyways. I'm switching out the fan blower motor and there is two wires, green and black, which one is positive? New to car electronics but in other systems they can be either. Is this situation always one or the other? Thanks for helping out a dummy. It's a 97 2.5 if that matters.

 

[jonny jeep]

Black is directly connected to ground.
Dark green is positive. If checking for voltage at the wires with ignition on, if the motor is unplugged you would see 12V with a multi-meter, but with the motor connected the voltage would vary depending what speed setting the controls were set at.

 

[Vinsane]

Black is directly connected to ground.
Dark green is positive. If checking for voltage at the wires with ignition on, if the motor is unplugged you would see 12V with a multi-meter, but with the motor connected the voltage would vary depending what speed setting the controls were set at.

Thanks bud. I will give it a go. Hopefully that's all it is.