Performed tune up service on minisplit systems checking all electrical components, refrigerant balance, unit start up, operation, shutdown. Found great room system low on refrigerant indicative of a refrigerant leak on system. Checked system over with halogen leak detector inspecting for leaks on both indoor and outdoor units and lineset between. Tightened flare nut and added 1 lb r410a to system and rechecked system for leaks. Did not indicate any leaks. Everything looks and runs great!