Salad cooler

[HVACTECHND]

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?

[coolerik]

Sight glass is clear? Sounds like txv

[HVACTECHND]

No sightglass.But if my charge was low i wouldnt think that high of suction?

[coolerik]

Id check subcooling...

[HVACTECHND]

What kind of superheat would be normal on this type of setup?And also they have the liquid line tied to the suction line purpose of this?

[coolerik]

That would be for extra subcooling, but sounds like a funky setup mabey someone converted from cap tube.. I dont work on alot of small stuff, whats box temp?

[HVACTECHND]

This set up is straight from the factory can tell by the insualtion on the txv. And not sure on box temp really isnt one. Its just a salad bar top they set plates on and the top gets frosted. No thermostat either they just turn in on with a switch at about 10 in the morning and shut it off at night and it just runs. Factory setup its a bohn condensing unit

[coolerik]

Has it got a cpr valve?

[HVACTECHND]

It has a txv reciever and compressor and honestly thats about it

[coolerik]

Check subcool

[HVACTECHND]

alright will do thanks ill report back tomorrow and ill take a picture to show you the setup

[coolerik]

Yah id like to see it, like i said i dont work on alot of small stuff, but im thinkin low on juice.. Pull the charge and weigh it in if in doubt.

[HVACTECHND]

alright you think low on that high of head though? not questioning you just wondering if there is a explanation behind it