Hello everyone, new to site. I have a problem with a 3 ton unit. This unit is a Trane air handler with Trane coil and it replaced the Carrier 2.5 ton that was installed when my house was built in 88. Prior to the replacement there was no problem cooling down the area (65 deg.) and the unit cycled regularly. Now the Trane unit runs all night before it ever gets to this cooling range. It is cooling approx. 800 sf, its located in the attic, and the area to be cooled is two BR and a bath on the north side and 1 BR and bath on the south side of the house. Also, the grille in the bath on the north side sweats. I have had it checked numerous times and just recently I had the plenum changed and an area of ductwork placed between the air handler and the coil to provide access for cleaning. The fan speed was changed at this time to HI from MED. Comparing the two units it seems to me that the Trane is not moving the same amount of air as the Carrier. The area at the return seems to be the warmest part of the area being cooled and you really can't tell that there is any air moving. I have checked for restrictions in the RA and all seems clear. I called the guy back that did the work recently about the sweating grille and he decided that there wasn't enough air moving through the unit. Every time that I try a different AC company there is a new story. I'm really frustrated with this situation. Any help will be GREATLY appreciated.