So….Forest for the trees and all that. I have a tendency to jump to the most complex of solutions when working outside of my daily routine and skip past troubleshooting steps 1-5.

After finding the drip pan half full in a day’s time, and water dripping from the bottom edge of the air handler all along the front, I pulled the evaporator cover off while running and after breaking a large amount of suction the pan started to drain as normal into the p-trap. Replace the cover and the water stops. Hmmm. Check air filter in intake…. sucked in and capped off the round duct. Basically 95% blocked. The cracks in the drain pan may be a problem but it should flow well enough now to limp along until end of life for the unit.

PSA: check your air filters regularly. Having four units with all different sized filters is a pain….