Air handler blower, motor, or something else?
ECM Motor Troubleshooting –yorkcentraltechtalk


  Troubleshooting the ECM motor can be very simple if you just remember that it's not just ON or OFF.  There are basically 4 problems that will not allow the motor to run:



There is no input power to the motor controller (high voltage input).
There is improper or no communication to the motor (low voltage inputs). This problem could be the CFM Programming control or board or the low voltage connector (wiring harness).
The motor controller (module) has failed.
The motor has failed (least likely of all the problems)