Performed single system, heat pump maintenance. Replaced the 23 x 20 x 1 filter. Cleared condensate drain line. Customer has been treating with bleach. I did inform customer that vinegar is also effective and less caustic. Inspected refrigerant level of system. The sound end wetness the customer had noticed is all a part of the defrost cycle. Technician was able to observe a defrost cycle while on site and system is defrosting normally. Electrical wiring and amp draws of the unit are also normal at this time and system is maintaining thermostat temperature normally.