Hi Michael, welcome to JOF.
Does it leak without the ac unit operating ? If so, its likely the gasket between the roof and AC unit isn’t compressed enough to seal. Remove the return air grill from inside the trailer and you’ll find 4 long bolts that secure the ac to the roof. The gasket is sandwiched between the ac unit and the roof by tightening these bolts. Note they might be overtightened causing the leak but more often, they’re loose. Don’t overtighten, just snug to squeeze to gasket.
If it leaks only when in operation, then the condensation tray drain hole is blocked. Remove the upper cover and look for debris.
2019 Pinnacle 36 FBTS
2016 Silverado 3500 CC SRW DuraMax/Allison
1975 Corvette for the sunny days n dry roads
2017 RZR for the rainy days n muddy roads