Expantion Valve Freeze Over

[tommy658]

What are the main reason for the expantion valve freezing over in a free standing Fosters comercial fridge?

[Brian_UK]

Could be a blockage at the valve, a shortage of refrigerant due to a leak or a failure of the valve.

All this is assuming that the airflow over the evaporator is correct and that the defrost system is operating correctly.

[tommy658]

Thanks for the advise. The refrigerant level and air flow are all fine. Whats the best way to test if the valve in faulty?

[Lowrider]

How can you be sure the refrigerant charge is in order?

If it's working ok and the expansion valve is frosting there doesn't have to be a problem! It can also be caused by bad or no isolation on the outgoing side of the valve. For sure if the temperature is low enough compared to the surounding are and it's moisture level!

[Pooh]

Is the door seal OK, it could be warm air getting in.

Ian

[acb]

Hi Tommy,

Reading between the lines here and correct me if im wrong, im going to assume that the fridge in question isnt working and the exp valve is frosting over and you want to know if this is normal, and if not, what can cause this.
In my experience of working on any integral with an exp valve fitted is, that if you suspect the valve of being clogged it will frost over but you can crack both flare nuts on either side of valve to check. No liquid, system has refrigerant problem. Liquid at inlet no liquid at outlet, faulty valve. This only works as a last resort and you have exhausted all other means of cause, and of course it stops an engineer from guessing.

kind regards

alex

P.S
If its an older foster cabinet and has had the compressor replaced on it at some point and its still the origional exp valve, it may very well be clogged.

[Samarjit Sen]

Hi tommy 658,

You have not stated as what is the status of the unit. Is it working and maintaining the desired conditions.

[tommy658]

The system runs fine at 1-4 degrees but then after a few days it strugles to pull down below 8. Each time I check it the valve is frozen over and Ihave to manually defrost it then its ok again. The fridge is opened frequently and is in a hot galley. I have opened the valve 1/2 a turn and it works for longer but still has to be shut down and defrosted every 10 days. I have 5 units in total and its only happening to 1 of them.

[old gas bottle]

i trust its had a new drier ?,i would pump it down and change it,valve as well ,running back and forth must be costing someone, is it off cycle defrost or heaters ?the coil may be getting sufficient heat to defrost but the shear material mass of the valve may not,you could try wraping it with armaflex tape or mess about with the defrost times to achive this. somewhere to start anyway.bit awkward when you cant see it

[Samarjit Sen]

As per Old Gas Bottles suggestion, please change the drier and the Expansion Valve. In the case of the Expansion Valve, ensure that the selection is proper. Which make and model is the Expansion Valve ?

[cretan]

As posted earlier,It could be an obstruction in the valve or moisture in the systen.Moisture in the system would cause the txv to ice at the orfice blocking flow.

[philfridge]

Hi unit is short of gas if tev is iced up after a few days regards phil