Does the voltage test not work for the power transistor, and if not is there a better test? The service manual has a procedure for testing the blower resistor (described wonderfully by kcarpent). However, this procedure is not listed at all for the power transistor.
I think this is the only thread on NASIOC mentioning the HVAC power transistor for auto climate control systems. Add me to the list for funky blower behavior.