My car's A/C had been going in and out intermittently. Sometimes I'd turn it on and it'd take 5-10 minutes before I could hear it engage and the air would get cold. Then it'd get warm and go another 10 minutes or so before I could hear it go on and get cold again. Anyways, the other day I noticed I had quite a bit of corrosion on my positive battery terminal, so I cleaned it and my terminal cable with some steel wool, and my A/C worked GREAT directly afterwards for a week or two, then it started going in and out again... and there's a little bit of build-up on the terminal again.

1) is it possible that the corrosion on the terminal would cause the A/C not to work all the time?
2) what's up with my battery terminal? The battery is a die hard (those are awesome, right?), a few years old. Does it need to be replaced or is there something else I should check?

If you're battery has gone through 3 years of texan heat, i would replace it. That is where i would start from reading your symptoms. Good luck!

I can't imagine why battery terminal corrosion would have anything to do with the AC not working. The battery doesn't do anything while the engine is running. It just gets charged back up. The alternator provides all the juice you need to run the engine and all the other electrical systems. Anyways, go to Autozone or Napa, etc and get a set of those anti-corrosion felt washers. They only cost about a buck for a set. You pull off the battery cables, put one on each terminal (after cleaning it with steel wool of course), and then reconnect the battery cables. They really do work.

Do what CMHX said for the battery. They also make anti-coorosion grease (I think it's just dielectric grease) that you can smear on the terminals to limit corosion.

As for the A/C problem make sure it's properly charged.
How check and charge the A/C system.

a/c is properly charged, that was one of the first things I checked. it's really weird