Volvo Repair: 95 960 Blower Motor Fluctuations / Failure, motor fluctuations, voltage fluctuations

Question
Mark,
My blower motor is acting up on me.  Upon start up in the morning, it seems to work well, but shortly after it starts become erratic and quits on me to negligible rpms (not complete zero speed).  The only certainty is that it doesn't like heat.  The warmer it is outside, the faster it dies. Between startup and death it spins up and winds down randomly, sometimes activates when I brake, other times when I accelerate. From your response to Herb's mail (9/9/08) I will jumper the motor to see if it's the culprit.
The next thing in line would be the solid state controller. Can you provide me pointers as to what tests / results I should perform? I have a basic DMM at home.
Best regards,
Jan.

Answer
  Jan, it almost has to be the blower motor itself. Only because you mention it changes speed going around corners and braking. That's a "physical" input and result(cause and effect). Not an "electrical" one. Do the jumper test to confirm. The solid state controllers fail generally all or nothing. It is still a possibility as nothing is absolute, but I would consider it a low probability?
   As an aside, you could monitor the voltage output of the controller at the fan leads. Watch for voltage fluctuations coinciding with the fan speed. That will help you rule it out. If the voltage remains steady and the fan speed changes, you have your answer. Do not forget that poor/low integrity connections or wires could be the culprit? They can be affected by "physical" inputs also.

Mark