Last year we found a blown fuse on a circuit,it controlled a/c few interior lighst etc but not the a/c doesnt work.

The light is on the dash but no cool air.Has anyone gone through diagnosis first before attempting gassing up.

Id like to see if the compressor is trying kick in or not first.

Any help would be appreciated

Well i believe the rad fan should come on when you press the button on the dash and you should hear the air con compresser click in and out. If its not doing this then i think your first look should be the pressure switch which has failed on mine so i have no air-con either.
Somebody will be along soon who knows far more than me.

if the pressure switch is not working or there is insufficient refrigerant in the system, the a/c will not operate. this is to protect the compressor more than anything else (as no oil, carried with the refrigerant) will be in the system. best bet is to get the system vac'd and partfill with the addition of UV dye so any leaks can be traced. I say part fill, as it will be cheaper if there is a leak, than fully filling only to lose it all through a leak. if still no joy (and no leaks apparent) consider replacing or testing the linear pressure switch (located at the bottom drivers side corner of the radiator, connected to a thin metal pipe) this can be removed with the system full, as there is a valve the switch connects onto so very little will escape.

hope this helps.