condensation problems with a trane XD-80

Is anyone had problems with too much condensation coming off the coil of a trane downflow unit. My secondary drain pan is full all the time. We have had trane enginers out to look at the problem, and no solutions. I am wondering if it is a design flaw from trane.

have you tried to wash the coil, if it is new there is a light coat of oil that could reduce water surface tension.Possible capillary tube blockage? Disconnect blower & see if all the evaporator freezes. Cracked pan?Good Luck.