My split unit (blower in the attic, compressor out back) hums but does not start. I tried to turn on the blower/fan only and I get the same hum and stops. Normally I would think that I have a bad motor, but if I keep trying on-off, on-off the fan and blower & and AC(compressor) will start and work fine. Then sometime later it will have problems starting up again. When the blower doesn't work, my compressor won't start up either.
Is it my motor or something else?

Thanks

You should look for a faulty fan relay in furnace or air handler , loose control wiring at relay or thermostat, bad fan motor capacitor and possibly fan fan motor.
Is this a heat pump or gas furnace ?

It's an ac blower unit only. Base board heating.

Fixed it! It was the motor, I took it out and brought it in to buy a new one but the store convinced me I could repair it for less. Waited a few hours and re-installed and everything is up and running. Out of curiosity, what would a new motor run? Got mine rebuilt for $75.

Depends on the motor, glad you got it fixed.