Is the box containing the evaporator coil supposed to be insulated? If so, with what? Mine is in the attic, is metal, and is very cold and wet.
Don't forget to replace the Schrader valves on both the low/high pressure side of condenser unit,there's a tool you can buy to remove the valve + replace without losing
Any shorted coolant R22a/ES22 canbe bought on ebay without a lic.
In unconditioned space it should be well insulated.
It wopuld actually be better if it was made from duct board and NOT sheet metal.
The higher mass of sheet metal can hold more heat increasing loads when the unit cycles (and the metal is about as close to R-0 as you can get).