I've just replaced my attic fan motor with a DAYTON 1/2 hp direct drive motor,permanent split capacitor #4m101 and a three speed pull chain switch.now when I turn it on nothing happens all it does is hum.so I'm wondering if the switch is not right to give out the right power or do I need to add a capacitor to get it to start? PLEASE HELP

I'm not following exactly what you did. Did you replace the entire fan unit or just the motor and switch assembly?

If you replaced just the motor, did you replace it with an exact replacement motor or just get a motor that you thought would work?

A quick test for the capacitor would be to start the fan blade spinning in either direction, then set the switch to "ON". If the motor starts driving the fan blades, then the capacitor is to weak to overcome the inertia of the blade assembly.

If the switch is connected according to the directions, the proper voltage should be transferred to the motor and cap. Question, are you using just the pull switch that came with the new motor or is there something else in the circuit?

The next possibly is that the motor lacks power to drive the fan although I really doubt that.

Can you get the model number off of the new motor, please. The Dayton motors that I see with that model numbers are 208/230 v motors which mean that you would have to have a 240 V circuit for this motor.

What size circuit are you trying to use this motor on?