We can recharge your unit to a certain degree, but where did it go on your closed loop system? If your air conditioner is in solid shape you shouldn’t be missing any freon. The question then becomes why?
Some a.c. units have a really slow freon leak, and others may not be so fortunate. We can determine what needs to be done.
The older the unit the less likely it will be cost effective to just add freon. In 2020, R-22 will be illegal to manufacture because it is not environmentally friendly, and in the meantime, the industry is increasing the cost per pound of freon. At some point, it becomes wiser to replace the R22 unit with the new 410A unit. The 410A energy efficiency is a positive attribute that the older units lack. Technology is getting better, but the disappointing statistics for longevity for new machines leave us ina conundrum. Consumer reports had an article on new systems and the best statistic stated almost “33% of these new systems would break down in the first 5 years”. What??? But I believe filling our landfills with old units is also an environmental issue that engineers are not considering. Regardless, we are adapting and learning just like you.