While I was out of town last week our downstairs Air Handler had motor issues that were described to me as "loud noises" while the air was on and eventually a failure. I removed the blower assembly and found the motor bushings shot and proceeded to remove and replace. I went to the local Trane service shop and they gave me a replacement GE fan that isn't the Trane model with the correct wiring plugs, etc.. But it does meet all the specs in terms of HP, speed, and size. The installed explained that they use these because they are good motors and fit a broad range of units the include the trane units. After installation, the unit worked, but overheated and shut off. So now I'm troubleshooting. Here are the differences in the wiring.
Original motor - Connections
1) Hot wire to the "medium" speed tap on the motor.
2) Black (common) wire from the control circuit to the same terminal on the capacitor as the yellow wire coming out of the motor.
Note: One the other side of the capacitor was a black wire that fed into the motor.
New motor - Connections
1) Hot wire to the "medium" speed tap wire (there was a connector on the original).
2) Black (common) wire to the white wire coming from the motor. This wire was show as the other side of the "line in" with the hot wire shown connected to the speed tap needed.
Note: on the original, I had three wires connected to the capacitor and on the new motor, just one. This extra white wire is the connection I'm unsure about.
Any ideas why the motor would get so hot?