A system for indicating on an electronic device that the refrigerant being introduced by a user to an air conditioning system has reached its optimum fill level includes a sensor device having a main body, the sensor device being structured and disposed for measuring a range of data; a wireless transmitter on the sensor device, the wireless transmitter being in communication with the electronic device for wirelessly transmitting the range of data to the electronic device; an electronic application configured for use with the electronic device; and wherein the electronic application is structured and disposed for visually indicating to the user via the electronic device the transmitted range of data in real time and audibly indicating to the user via the electronic device when the transmitted range of data reaches a predetermined value.