You should never have to add refrigerant (Freon) to your central air conditioning system, unless there is a leak in the system.
If your system has a leak, a service technician should never be "topping it off" with refrigerant. The system needs to be leak tested and the leak needs to be repaired.
A refrigerant leak WILL harm the compressor, cause the system to draw more electricity, provide inadequate cooling and/or heating if it is a heat pump.
Many refrigerants are being banned due to the ozone depleting chemicals. That is another reason that ALL refrigerant leaks need to be repaired and not topped off with more refrigerant.
Refrigerant repairs on older central air conditioning systems can get costly, so you may be better off replacing your system.
If you have any questions about your central air conditioning system, contact our office: https://www.airinchvac.com/free-estimate.html