JWI did that already, no change. Trout, my scale is also that accurate but a 1/2 oz is a pretty sizible over or under charge on a 4.25oz system. tgood the heat exchanger appear to intact, but you may have hit on something, it may be too short. Where the heat exchanger leaves the cabinet it seperates, cap tube to the dryer and the suction line drops to form a 4" trap then loops around the condensor/fan assy. to the compressor
the overall length is approx. 18".
The puzzling part is why the line thaws when the evaporator cover is removed.