House is only 6 years old, 2 units; 1 upstairs, 1 down....Seems like the the unit upstairs keeps freezing up (or whatever you call it)....where the pipes to the outside fan unit seem frozen and it stops blowing cold air....The last two years, I have had guys check it, and it seems to be low on Freon (sp?) or whatever agent is used now, and I would like to solve the problem for good. I also want the guy to check the unit in the attic...seems to be draining out of the reserve pipe and not the primary....Anyone do this work?