Was doing a google search and found your forum.
Our maintenance crew was going through a building that we just recently took ownership of and cleaning it up before allowing rentals. One of my guys noticed we have an 3.5 ton Rheem AHU that is marked 4 years old, matched up with a new(hand written start up date of March 2008) 3.5 ton Haier condensing unit. We noticed the suction pressures running a little high, but the discharge pressures seem normal(80/225 on a 95deg day w/80deg space temp). The unit ran all day long and wouldn't get below 78deg space temp. I though maybe we might have air in the system, so we changed out the liquid line drier and pulled a good vacuum; that didn't change anything. I am assuming the AHU isn't a 13 seer and that the new condensing unit is a 13 seer minimum. Looking for answer to a problem none of us have experienced before.
Thanks in advance