Outside unit comes on... but airhandler doesn't blow air... can hear a hum noise... nothing stuck in fan

Either you fan motor, fan belt, or fan relay is bad. Sometimes it is in the t-stat. The G terminal is not supplying 24 volts to relay. If when you first turn on unit you hear a click inside the indoor unit, the relay is probably okay. See if the motor turns freely. What kind of indoor unit is it? A gas furnace or AC air handler? Does it work on heat? If the fan is bad you replace the motor and capacitor. The blower unplugs and slides out. You can slide it out and take it to an ac parts house to get a replacement. If it's a 5 ton ac unit it is a 1/2 horse fan, 3-4 ton it's a 1/3 horse motor, and if smaller than that it's a 1/4 horse motor. You can go up in size, but not down. Motors are reversible on many replacement motors and the fan turns in the direction the blades are pointed. DrTom4444