Performed cooling tune up. Flushed drain line. Cleaned condenser coil. Checked all major components and system operation. Found that air filter is incorrect size and fell into return duct causing system to have no filtration. Correct size needed is 13x21x1, recommend IAQ 1000 air filter, customer declined IAQ 1000 and will purchase and replace filter themselves. Found evaporator coil very dirty, chemically cleaned it. Applied Teflon treatment to evaporator coil and blower wheel. Found very little insulation on suction line outside, replaced it with new suction line insulation. Found system had no flood protection, installed wet switch flood protection unit. Customer stated that line set would freeze in heating mode over the winter, they pulled disconnect and have been running electric heat only. Turned system to heating and found that it is calling for reversing valve and running in cooling on call for heat. Verified board has failed with AirTemp tech support. Ordered defrost board cov