how ever you are getting this unit and you friend with thirty years in the trade doing it
at least you being responsible to the enviorment by repalcing that unit
water sorce with refrigerant leaks can contaminate the water and go back into the ground and cause more problems
once a unit like yours leaks it should be repaired before adding freon or just replaced
in this case that is my top concern
the part you discribed sounded like some type of filter set up or flo control