That wasn't it
I had the blower housing off and directly poured some water over the coil - and it came out under the engine just fine. So I'm not blocked up. That leaves me with trying to see the other side (the underside) of the ac coil where the critter could have gotten in from the inside of the car. But I haven't seena a way to get to that area of the housing.
1986 560SL 145k