[C320-list] AC

[wflowe3 at aim.com]

I'm having some intermittent problems with my evaporator coil icing over.  Thought I'd cured the problem by making sure all ac vents were open but it iced up again yesterday afternoon (after it had run fine all day).  Any suggestions. It is a Cruisair  system that sits on a shelf above the fuel tank in the starboard aft lazerette.  Running the unit in the heat cycle defrosts the coil in a few minutes but I'm trying to figure out why it freezes in the first place.  Any ideas?