If there is any freon left in the system, DO NOT release it to the air. You can be fined up to $25,000. Take it to a shop that knows what they are doing. If the system is empty, the desiccant should also be changed. That is what absorbs moisture in the system and if the system has had air in it for 2 years, it will be full of moisture.
A vacuum has to be pulled on the system before filling it. Air in the system is terrible for the efficiency and contains moisture (not good either). Have someone check for leaks after it has been recharged. If not, you'll be doing it again in a month or two.
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