Cadillac Repair: 89 deville blower motor, blower motor resistor, salvage yard

Question
I have an 89 deville.  My mechanic changed the blower motor.It did not come on. We then changed the the blower motor resistor,(on the firewall). The blower motor came on when it wanted to, and did not shut off, even when the vehicle was shut off.  Then it stopped working.  I purchased a used interior control from a salvage yard.  Still no change.  We have power to the blower motor. We have changed both the blower motor and resistor again.  Still no change.  Thanks

Answer
Hello,

I really do hate these inherent problems Cadillac came with. The problem working with junkyard parts is that you don't know if the part you are replacing is any good.

The problem with not shutting off was very common in the resistor block module.

What bothers me here is you  have power to the motor and will not run. If this be true, there are only 2 possibilities. One being a bad motor, the other being a bad ground for the motor. There are no other options if you have power to the motor.
Are you absolutely sure that the motor is installed correctly where the squirl cage is not binding in the housing?

Now, if you didn't have power- the resistor module could be bad and the one thing you did not change, could be a bad computer too. When these Cadillacs get old, they can be a nightmare to diagnose and repair. That is why I traded mine off for something less complex.

As I said, if there is power to the motor it should either be at 12 volts for high and less with a slower blower speed.

Ler me kow how it turned out.