Recharging isn't an option - at least with the factory setup. It's possible I guess to add a charging port (it pierces the line as you tighten it down) and add refrigerant, but Dometic designed these units to be non-rechargable. They will tell you to replace the upper unit.
I'll tell you, for what it's worth, to strongly consider replacing it with a Houghton and forget Dometic. The Houghton is far quieter and by all accounts more reliable.
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