algee accumulated on the drain pan inside the unit.
shut unit down, turn off breaker
put on your PPE equipment and adhere to all safety rules and practices
remove the side panel to the coil section using a drill and either a 1/4'' socket or a 5/16
inspect the white pvc drain pan, clean all algee/mold and disguard. pour a little water onto the pan, to check and see if it is draining out the drain
then, if it is , pour 1/4 cup bleach onto the pan.
if it is NOT draining, blow the drain pipe out with compressed air, then pour a litle bleach to kill mold
at this time, check the coil itself for dust/dirt, crap, and clean the coil, BEING CAREFULL >>>NOT>>> to bend the fins
If you do bend fins...use a simple everyday COMB [[hair comb]] to straighten out bent fins ...!!!!GENTLY!!!!
put all back together. turn unit on