1992 Isuzu Amigo compressor drive belt tensioner

First off, this is the 2.6L engine for the Amigo. My question - Is there a special trick to loosening the a/c compressor belt tensioner for this vehicle? I tried to loosen the large front-facing nut with no luck. The long bolt that runs along the rear of the tensioner loosened pretty easily, but the tensioner still won't budge at all. The vehicle has been garaged since 2002 and I finally got it running (VERY long story) and it did well for 2 days, but when I was on my way to the parts store to get all the belts and tune-up accessories for it, the altenator/fan belt snapped. I have all of the other 3 belts off, but this 4th belt is giving me lots of trouble. If I can loosen that tensioner, I think I'll be on my way. Thanks in advance for any feedback you can give me.