Is the thermostat switch set to proper positioning (heat or cool)? Is the set-point above or below the room temperature?

Is your furnace plugged in or is the power switch turned on? The air-conditioner needs the furnace to circulate the air.

Is the air-conditioning disconnect or breaker turned on? If you know how to check the fuses, see if there are any blown. If you do not know how to check the fuses, call a technician.

Is the furnace filter clean?

Are the air registers open?