a friend asked help about his furnace blower emitting a screeching sound during operation and then just stopped. i went over and tried to rotate the blower by hand - resistance to free rotation was present. removed the blower assembly and dismantled motor. no lubrication on both motor bushings. cleaned and lubricated bushings and re-assembled motor and fan. now it rotates freely. tried to start the furnace - burner started to fire but the motor just hums till the burner went out. rotated the blower - free! the motor is capacitor started - could not locate any nameplate for both the motor and furnace. what might be the problem? it is getting colder. please help!

labman

Some motors have a centrifugal operated switch in them that must release for the motor to start. Its contacts may have welded when the motor was overloaded from the dry bearing. I haven't had much luck getting such motors to run right very long.

Ordinarily I would say a capacitor start motor that hums rather than starts has a bad capacitor. I find it doubtful the capacitor went bad while you were cleaning up the bearings. You might carefully check the connections to the capacitor.