Ok guys here what I got its a salad top cooler. It has an evap with no fans its encased in the metal and just gets frost on top. Issue is top is not frosting. Put my gauges on i have 51 suction 300 head R 404A. Superheat is incredibly high at 50. Now I suspect bad txv. I tried turning in the stem with no change. Condensor was cleaned. Has reciever so i didnt measure subcooling. Does my diagnoses sound correct?