Two system. Heating tune up performed today. Both systems are Trane heat pumps with air handler installed in 2013. All electrical connections are tight with no corrosion. Biological growth is present inside of both air handlers. Highly suggest a level 2 duct cleaning on each system to clean both duct systems, both blower wheels, both evaporator coils and the interior of both air handlers. Downstairs system has a drain switch but the upstairs system does not. Suggest installing a drain switch on the upstairs system to help prevent water damage in case of a drain blockage. Both compressors, condenser fan motors, reversing valves, and defrost control boards are working properly. Both systems are running and cooling the home upon departure.