The condensation is supposed to drip into a trough under the evaporator. This is located above the air intake filters you referenced. A rubber drain hose connects to the end of the trough and typically exits somewhere in the street-side wheel well. When operating properly, you should have noticed water dripping or a wet spot near a tire. A common cause of failure is if something stops up the drain hose. An insect nest in the end of the hose is a likely culprit. Locate where the hose exits the trailer and probe it with a thin screwdriver or coat hanger wire. If not there dirt/lint/rust may have blocked the exit of the trough at the point where the hose connects or the hose may have come off the nipple.
The connection at the trough is not easy to see or access so hopefully probing the end of the hose will solve your problem. Some have reported success by carefully applying compressed air to the hose to loosen any blockage at the trough connection. Whatever you do, try not to damage the hose... It looks like a pain to replace.
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