For the evaluation I showed up to the customer's home and the coil was freezing up. Filters were good and not obstructed so I gauged up where I had a below freezing saturation temperature and an extremely high superheat for this piston meeting device indicating the system was low on refrigerant. I spent well over an hour leak searching the evaporator coil and could not find a definitive hit on a leak. I went to The Outdoor research to condenser with the same results and when I opened up the service ports the saturation line straighter valve was just loose enough to where I could see refrigerant bubbling out and on the inside of the cap it was full of refrigerant. Our place is trader valve and charge the system to a 24° superheat.