hvac blower vs capacitor, does my conclusion make sense?
 

hvac blower problem, or maybe just the capacitor. Ruled out thermostat (I think), outside comes on, but hvac blower doesn't start...neither on auto or "on". hear low hummm at the unit. Opened cover, tapped on relays (at least what I think is the relay on the board), unplugged the cool wire connection reconnected, manually spun fan freely, reattached cool...and voila, it worked. Does this sound like it was a stuck relay, or maybe the capacitor? The blower motor does sound like it started up pretty slowly? I guess if I now leave thermo to "on" it will stay on until I can resolve the problem?

Could be the relay, or the capacitor, or the motor.

Or all 3. :yes: Next time don't tap on the relay. Carefully try spin the motor gently to see if it was stiff. Should be able to spin it with one finger. Probably the motor is seizing and the capacitor dies with it. We replace both at the same time.