go over
Re the Plenum. I had this problem & found the air intake top edge is bit low as well as some of the fixing screw threads needed sealing.
Restrictions in the O/flow drains means the water can top the Air In Duct & if the fan is operating that will only make it worse.
Anyway that was my problem & fix & then the Alpine Lights metal started to rust out & that was fixed when it went in for other panel repairs. Up to the time it was flogged off these points proved most satisfactory.

