99 Pontiac Firebird AC not working.?

[RCompService.webs.com]

I put Freon in it, and it works for a few hours, then stops.
I'm guessing a Freon leak or something of that sort..
I'm not expert on Car Ac's, but would "Flushing" the AC help at all?
I put Dye in it to find a "leak", but with no results..

Thanks in advanced.

 

[melsg5]

It sounds like a leak, dont see how flushing would help. AC repair shops have a freon sensor to find leaks if the dye doesnt spot it.