Air Conditioning - condensation on floor

My current AC unit is a 3 year old air conditioner unit and is upstairs; however, the problem has occurred with 3 different evaporative coils. The condensation water falls straight down from the coil instead of entering the pan as it should. Two a/c companies have installed new evaporative coils and still haven't solved the problem. One company put a pan on the floor to catch the condensate. This pan has a float which will turn the unit off when the pan is full; however this doesn't solve the problem of the condensate dropping straight down off the coil instead of going to the coil pan and being carried out the drain pipe. We have to dip out the water when it fills to be sure it doesn't overflow. Another detail: There is a larger unit for the downstairs cooling, located beside this unit in the same closet. It works perfectly normal.
One person has suggested that maybe the evaporative coils themselves are not level, which I will check tomorrow. The problem I've described was originally discovered when the a/c unit originally in the house started leaking through the ceiling downstairs about 10 years ago. Any suggestions would be appreciated.