96 Buick Park avenue AC

I would suspect a faulty blower control module. Have you tried one yet?

that was my first thought. I replaced the blower control module and the problem was still there.

When you checked the voltage at the blower motor, did you use the ground in the same connector? At the blower control module, I am showing battery power at red wire, ground at black wire, blower speed input from the HVAC programmer on the gray/black wire, and the blower out on the purple wire. Another item in the circuit is the HVAC programmer, it supplies a blower speed control output to the blower module, and also recieves a feedback from a splice on the purple wire through a fuse. I will attach the schematic.

The schematic really helped.
The power from the control module to the fan and feedback fuse is 1.91vdc from the purple to the black lead at the fan motor.
The red to the control module is battery power.
The gray/black wire has just under 11vdc on it.
The purple at the splice is a good connection, the 10A feedback fuse is good.
The only things I have not checked are the connections to the HVAC programmer, or the programmer itself.

In the process of checking things I put an ampmeter on the fan motor and powered it direct with 12vdc to check the motor. The current was at 15amps, is this normal?
Where is the programmer located? I looked under the dash on the passenger side and there are about 3 or 4 electronic boxes under there.

I would think anything less than 20-25 amps sounds good. Looks like it is visible and serviceable with removal of the instrument panel compartment(glove box). This blower control module that you replaced, where was it from? With what you have for readings, It seems like a bad blower control module. Is the voltage the same on the purple wire when using a known ground like the battery negative post?