And the walls of the frezzer are frosting evenly? If so, give it more coolant, take it up to 10 psis, clear little by little and taking care of the amperage of the compressor and the uniform frosting of the walls of the frezzer, if you see that the amperage rises, you no longer inject coolant and you would have to uncover again the system and make sweeps and filter change again, now if you see that the freezing of the walls of the freezer are not uniform, and do not inject refrigerant, that system is most likely, that the filter is semi-covered and maybe moisture circulates in the system, regards