Troubleshooting Notes
Open circuit voltage is measured with the blower disconnected from the wire harness. Closed circuit voltage is measured with the blower hooked up to the harness. The medium and low voltages will be 115v for the first 4:15 if the unit has the new control box (part 230-2070). Minimum voltage to the motor should never be less than 74v. If so, replace the control box.
If your motor runs hot to the touch or vibrates, typically this means that the motor needs to be replaced. There are instances where a controller may be sending a modified signal to the motor. Before replacing the motor, bench test the motor with 120 volts directly from a test cord, see if the blower still operates the same way. If the performance improves, such as less hot and no vibrations, replace your controller, otherwise replace the motor.