Evap Coil drip pan drain holes are plugged up
Condensation from Evap Coil is being pulled over by room fan blower into discharge plenum and dripping inside
Have to remove roof shroud and then open the 'sealed' compartment where evap coil/drip pan is and clean the drains out
Also check that A/C Pan is not sitting on roof.
If the hold down bolts (under inside ceiling grille) have been overtightened then the roof gasket has been crushed and pan is blocking drains
(gasket should be roughly 1/2" thick--new ones are an 1" thick prior to installation)