1998 Jeep Wrangler AC

Ok. My Jeep's AC will not cool.I've been told that it is NOT the compressor, but possibly a switch, which can't be confirmed until the dash is taken apart. Is there another way to possibly fix this problem? My concern is that my mechanic can't give me an estimate on price until he goes in and looks, but what if it is more than I can afford? I hate for him to take it apart for nothing.

Thanks!