If it is the outdoor fan, it could be a couple of things. 1. Bad fan capacitor 2. Bad fan motor 3. Loose wire If indoor blower the same apply, but it could also be a bad fan relay.
Either mounted to the fan or in the electrical compartment on the outdoor unit.
Instantly.
No the out side fan is for venting heat away fromt he unit.
yes
The outdoor unit only runs in the AC mode(unless it is a heat pump). If you have the system off and the fan on, the outdoor unit should not be on. You can run the indoor fan only without harming the system.
because you're dumb
The inside fan blows air through the ac coils to cool the air. It should be on a separate breaker or fuse circuit from the outside unit. See if there is a fuse box on the side of the inside unit and check the breakers in the house main breaker box. Also stand quietly beside the inside unit and listen for the fan motor running. If the motor is heard running then either the fan drive belt has broken, or the ac coils are clogged preventing air from flowing.
If the fan is working, then probably there is insufficient gas in the ac compressor.
fan commpressor coils fron
In the central ac system it could be a few diffrent things that are not working, that is causing the fan not to blow. Their could be no power to the outside unit, a bad contactor, a bad capacitor, or your high pressure switch could be shut down.
1. Bad fan motor 2. Bad fan capacitor 3. Contactor bad 4. No power to outdoor unit.
The ac compressor's clutch may be blown. If so the compressor will not spin and provide air. The fan could also have a bad motor which will stop the fans from working.