Performed routine maintenance on a 10 year trane package unit. Checked filter, checked thermostat, checked elements and blower amps, checked the evaporator coil, checked drain pan and blew out the drain line, checked/tightened electrical connections, checked capacitor, checked fan and compressor amps, checked pressures and reversing valve, cleaned condenser coil. Refrigerant levels are normal as are amp draws on compressor. Start assist is good and ultraviolet light is operating. Defrost and electric heat operating properly at this time. Evaporator coil is heavily rusted and will be an issue to the sealed system in the future. Terminals for electric heat are heavily rusted as is compressor connection. Due to age, lack of warranty and costly future repair,replacement is needed.