The air being blown out the vents may just be air drawn in from the outside of the car and is not cooled down/refrigerated. Do you hear the air conditioning compressor engage when the a/c is turned on. The a/c compressor is driven by a fan belt at the front of the engine, the compressor has a "clutch' on the front of the compressor that electrically engages when the a/c is switched on by the driver. The problem could be electrical or it could be a problem with any part of the a/c system. It needs to be investigated by someone familiar with air conditioning but this system is not complicated on this car.