RTUs/MAU/SS/MS – Biannual (2 x per year) Visually inspect.; Lubricate as needed.; Check filters.; Check, adjust and / or change belts.; Check controls.; Check condenser fans.; Check the thermostat and temperature rise. (Test Heating / Cooling ); Check indoor blower operation.; Check venting and outside air damper operation.; Check heat exchanger.; Check burners and operation, clean if required.; Check pilot and operation, clean if required.; Check compressor.; Check crankcase heater.; Check oil level.; Check refrigerant charge.; Check condenser coils and evaporator coils.; Check economizer.; Check condensate pan and traps.; Clean condensate pan and traps.; Clean condenser coils (biannual).; Clean evaporator coils (annual).; Submit Preventive Maintenance Report.;