Let me begin by saying I don't know the first thing about HVAC. Hopefully someone here can help me. I've got and air handler mounted vertically in the garage. It has a severe water/moisture/leak problem. The return air duct in the living room has a clean filter, and is on the backside of the wall where the unit is mounted. Air returns from beneath and goes up through the coils. Is there suppposed to be a filter before the coils (inside the unit)? I'm asking because there isn't one; and the outside of the unit has a sticker on a removable thin strip of metal that says "filter". I crawled into the return air hole and inspected the floor for dampness and there was none. There was condensation on the coils as I looked up- and the edges of the yellow foamboard insulation were damp. There have been times where the garage floor looked as though someone spilled a bucket of water. The surrounding drywall is damp and moldy, and puddles seem to seep from the bottom of this area. Any ideas? Please??