You can get line tap valves that wrap around the refrigerant line and puncture allowing you to connect a guage. This is supposed to be a temporary setup because it will leak. You can also get service port installed but all of the refrigerant will have to be removed before that can be done. Getting the refrigerant will be the hard part depending on what your system uses. Do not mix different types of refrigerant. The only type you can buy without and EPA CFC certification card is R134a.
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You can get line tap valves that wrap around the refrigerant line and puncture allowing you to connect a guage. This is supposed to be a temporary setup because it will leak. You can also get service port installed but all of the refrigerant will have to be removed before that can be done. Getting the refrigerant will be the hard part depending on what your system uses. Do not mix different types of refrigerant. The only type you can buy without and EPA CFC certification card is R134a.