I used a some Wrigley's Extra gum I'd chewed up to sorta seal off the little hose pushed into the drain tube.
Gotta try some A/C fin cleaner on the condenser as well.
To try to eliminate the old musty odor, I used a can of the official Toyota stuff.
1 can wasn't enough. Next time I bought this stuff
https://www.amazon.com/FJC-5914-Foam.../dp/B002EAKX88
which appeared to be what the Toyota stuff really is, except cheaper.
Before I did the second pass, I removed the blower motor, and using a mirror to see into the evap chamber, sprayed most of a can of CRC Lectra-Motive cleaner directly onto thr evaporator assembly, and then used about a can and a half of the FJC stuff by the conventional method through the drain tube.
After all this the odor was 97% quelled, but I plan to do it again as a preventative and...yes, if possible, I'd like a little more cooling power out of the A/C.