ought to be drain holes,unless clogged with dirt,or rust,
I picked up a heavy dog old whirlpool from the alley,, did a lot of cleanup to it,,found it did not drain water properly,, took it out of the window opening,up ended it,carefully drilled 4 holes without damaging parts inside,
a carbide tipped drill will do the job.drains nicely now.
the unit has to be pitched. a few degrees toward outside,