Customer has 4 y/o 2-zone Goodman furnace matched with 3 y/o Goodman AC that operates for whole house. Furnace control board indication light was not displaying although power was supplied to board. Reset power from door switch and indication light for furnace control board came on. Noticed some browning and bubbling on back of furnace control board. Also, noticed that zone board and furnace control board are using same transformer, which should be separate. Zone dampers were not wired correctly. Dump zone used instead of bypass damper. Water protection is poor. Blower wheel cleaning needed. Ductwork looks to be insufficient for 5-ton AC.