My strongest suspecion is that drains are improperly trapped and/or very short before opened to daylight. In addition to traps on lines,some arrangements must not have an open tee on lines. If you see an inverted T in the lines,temporarly plug the opening to see if that cures or improve's leak. The inclosure must be reasonably air tite which can be helped with foil tape. As air flows through handler,which does it pass through first,secound and third ,blower ,filter, evap coil? Was blower,coil and strip heaters replaced as a unit or was part of old handler retained? If this turns out to be the problem a baffle can be installed on condensate pan as last resort. By rook or crook,you must have a filter or things will just get worse.

16" O.C. would probably be better. You're probaably using 1/2" galvanized lag bolts and washers. I think you'll be OK. The Porch Guy Here is a link that might be useful: My Album

We might completely replace the paneling at some point in the future, but doing that right now would become a much bigger project than we want -- getting rid of the fake beams, re-wiring the lights, possibly having to re-do the ceiling depending on how the fake beams were attached, etc. We decided to go with Patricia Cowell's idea of using a small piece of trim to camouflage the transition from drywall to paneling. It would just be a short piece just above the edge of the doorway trim, so it won't be too jarring.

It is the drain line that clogs up with biological growth. But the switch never gets wet even while it is leaking. I can manually push the switch up and it shuts the unit off. But the water from the drain pan never makes it to the switch to turn it off and nothing clogging it. The unit is relatively new. Has a plastic drain pan. Service guys can't figure it out. Here is a pic. You can see the switch on the right and the drain line on the left. I am posting here for inspiration on why the switch is not getting water while the unit floods. I am wondering if the drain pan is not level.