You said the outdoor fan is not running, can you hear the compressor running? If you can hear the compressor running then start by checking the fan capacitor. If you can't hear the compressor, then check the breakers or fuses or disconnect. One of these should be located near the outside unit. If you look at the contactor you can see the contacts. When the unit is off they should not be touching, when it is on then the moveable contacts should be pulled down and touching the stationary contacts. You can get some on at the thermostat while you watch the contactor to see if it moves when they change the thermostat to call for a/c. Let me know what you find and I can give you more advice.