I had a Gibson central air conitioning system installed in Oct.2011 the air handler is located in my attic and compressor is outside . the main trunk is metal and insulated and branch lines are insulated flex . I used it a couple of times that fall then closed up for the season when I started up in 2012 around may or june I noticed not as much air as there was in oct. so I called installer he found unit all wet full of condensation and fan was corroded .I had closed off all vents and put insulation foam board in return to keep heat out of unit during winter months . we had to replace air handler no one could figure out why it was all wet from condensation . so I installed a roof fan that runs on temp and humidity to control the space in the attic I also made magnetic covers for supply vents to keep warm air out during the heating months. The new unit ran fine all of the 2012 season . I closed up again fall of 2012 this time I used the magnetic covers, kept the attic fan running and insulated return in hopes not to repeat the problem . I just checked unit again and found it all wet from condensation fan is dripping, pan has water in it from all of the moisture . Has anyone ever seen this problem before if so how can i solve it I don't want to have to replace again this year i have not had a troulbe free startup yet. installer was frustrated and had a hard time getting replacement fan unit from the company they said it was not their falt unit was wet it was the space it was in.Please help????