I recently purchased a home (1300 SF in Houston, TX) that was built in 2005. The air handler in the attic is a Gibson 3 ton unit and the outside condenser is a Tappan. The unit has 2 different zones: zone 1 being downstairs and zone 2 being upstairs. The unit also has a barometric damper from the return side to the supply side which I don't believe is working properly due to the fact that it always half way stays open. When I first moved in, it took about 8 hours to cool the house from 81 degrees to 73. When I first had my home inspection done, the inspector noticed that the delta t was low and suggested that I have the evaporator coil replaced. I wrote that into the repair list and sure enough, the seller had his home warranty company come out and find that the evaporator coil turned out to not be leaking. I had the HVAC company who the warranty company dispatched come back out to do a recall to check the system and they then stated that I need an all new zoning board as well as new zone dampers to try and increase the air flow throughout the system. They also recommended that I clean the condenser coil off. I cleaned off the condenser unit (which was beyond filthy) and noticed the house cooling better upstairs but really no change in the down stairs. I then called the home warranty company again for a second opinion. The second company came out and added about 2 lbs of refrigerant to the system. There has not really been much of a change other than the liquid line feeling "beer can cold" the way it should. I am not sure if my problems are one single problem or multiple problems put together. Any suggestions to the poor air flow problem? If so, does it affect the delta t in the system? Could the barometric damper be the problem since it is not functioning correctly? I also want to note that I have been getting a lot of condensate in the drip pan and can hear it in the duct running from the supply side to the return side.