When I turn on my central air conditioner, the air that comes out feels like a fan, rather than cool air. What's wrong? And how do I fix it?

1. The compressor may not be running

2. The thermostat may not be calling for cool (unlikely if the fan comes on)

3. It may have lost some Freon so it's not cooling any more.

It might be possible to fix the Thermostat yourself, but handling Freon (#1 or #3) requires a licensed professional.

Probably nothing running but the fan on your furnace/airhandler running
Check the breakers for a/c, turn completely off and back on again
Sometimes there are a second set of breakers outside close/beside the a/c unit