Had a goodman 3 or 3.5 ton 13 seer installed about a year ago. Works fine except that the upstairs is about 5 to 10 degrees difference on the plus side all the time,(cooler when air is on, hotter when heat is on). I have switched the summer,winter switch in the ducts like normal, kept the filter clean and still the same. The only thing I can think of is that when it was put in, the installer set the blower motor to its highest output so the house would heat up faster since it was put in because of an older hvac system failure in the middle of the winter.Could it be as simple as changing the dip switch settings to bring the blower back down to its normal range or something more involved that needs to be looked at by the installer.

Try switching your fan from AUTO to just plain ON for a few days. Bet you will see more evne temps and usee very, very little additional electricity.