I need some help. My company located in South Florida installed a new 5 ton split system with the air handler being located in the attic. Since then we have been back about thirty times for not cooling enough, customer wants it kept at 68, and leaking at ceiling, unit is sweating. Because main complaint was unit was not keeping up with heat load and we had so many problems with it we even replaced the new air handler with a larger model and therefore a larger coil. Now the sweating is so bad that the mastic will not dry and the complete cabinet is soaked. We had cork-taped all seams at installation but still have a major problem. After some research we sized up the existing ductwork and found it to be rated for 1300 cfm. Since the air handler is 2000 cfm we feel that this is the problem. This is a huge home and this only one of three systems. We suggested updating ductwork to the owners rep and they do not want it done. Now they want the unit removed and a full refund, stating that another contractor said the ductwork is fine, I have requested copies of his report. Any thoughts on this would be extremely helpful.