a/c doesn't seem to drain properly

[Pat]

Another a/c maintenance question.  I had the roof cover off today, and I think I found the drain hole underneath on the passenger side toward the front.  It was impossible to see if the hole was obstructed, but it felt clear.  However, I don't think my a/c drains properly.  It used to drain onto the roof and down the side of the motorhome, but it hadn't been doing so for a while, and I noticed when I moved the motorhome that water poured off the roof suddenly.   

Above the hole there seems to be a trough down the side of the a/c unit.  Above the drain hole the trough has some soft, black, putty like material. Is water supposed to collect in the trough and drain through the hole below?  If so, it doesn't.  Think the putty is blocking that?  I can't tell, I can't see a hole.  Should I clear the putty out?  Or is it  there to seal the trough from water draining into the hole below from elsewhere? 

I realize this is difficult to picture.  I have the paper and electronic versions of the manual and installation instructions and the parts listing and diagram for the unit.  There is no mention of the drain hole at all.  Is there a better technical manual for these air conditioners?  Oh, it's a Dometic Duo Therm Penguin heat pump 630515.321. 

In the maintenance section, there is no mention of the drain hole.

Thanks.

--pat

 

[Gary RV_Wizard]

Try pouring a bleach solution down the hole to kill the algae that often accumulates within the drain.