Air conditioner wont turn on?

I got a 2001 subaru outback for super cheap, but the ac wont work. I press the button, and the light comes on, but the compressor never engages. Any suggestions?
Update: I would take it to a shop, but i only payed $700 dollars for the car, and i really don't want to put any more $ into it. I'm just wondering if there was an alternative way to fix it.
11 answers 11