A/c evaporator coil drain, should be a straight little tube (3/8" or so?) sticking horizontally out of the lower cowl area about in front of the passenger's seating position. Might need to get under the car to see it, but it's somewhere in that area.
The cowl drain(s) are separate. No water should be getting into the a/c case from outside, as it has to come through the rh cowl vent area to get there. Which also means it might also be inside the car if sealing is not good. The cowl drain is usually on the rh of center middle-height area of the cowl. A simple flap of thin rubber. Enough to keep hot underhood out of the cowl, but thin enough to not have any real resistance to water in the cowl coming out easily. Seems like there are also some cowl drains that also send water into the hollow rocker panels to drain out of holes on their bottom side?
Might need to remove the cowl screen and search the inner cowl area for some accumulation of leaves or similar?
Do ALSO check the bottom of the a/c case for gasket leaks, too. The stiffer rubber foam gasket does not, by observation, seal against the metal slip-on nuts very well. Our '72 Newport Royal had leaks. My '70 Monaco did not, BUT when I pulled up the rubber factory floor mats, there was moisture under them in the carpet.
Please advise of your investigation and findings,
CBODY67