I have a trane xe1000 - model TTR730B100A0, the fan condenser motor failed. Replaced with a new one. Tured on the power to the outside unit, turned on the A/C, fan came on. Turned the A/C system off, the fan went off, and then heard a faint humming sound. Still had the top loose, so I lifted the side where the capacitors and the contactor are located - no sound there! Leaned over the top of the unit, still hear the humming. It's a very low hum. I have to lean over the top of the unit to hear this humming. What's crazy is that it sounds like it's coming from the motor. Before I installed the motor, which by the way was an OEM replacement. I checked end play and ease of rotation on the shaft, seemed fine. Pulled the outside breaker - disconnected power, no sound. Any thoughts? I can't tell if the compressor kicks on, with the sound of the fan coming on and the air rushing by, I can't distinguest the difference.

Capacitor may be a problem, check if fan can spin freely.
Then safely give fan blade a push start, if you can't do it safely, don't do it.
Also, be sure air is blowing out the top, or a pair of wires may need to be swapped on the fan to reverse direction.

The fan can spin freely, it's a new oem replacement. As stated above, before I installed it I checked for end play, ease of spinning by hand - no problem. The air is blowing out or rather up.
I have a new capacitor on order, I'll get it tomarrow AM. And then install it.

Good Luck