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Drew
30-11-2016, 07:26 AM
Hi all,

im working on a meduim size freezer which holds 90 kg r404.
My colleague has said that he thinks it's short of refrigerant due to high superheat, low head pressure, low suction, liquid line temp shows no sub cooling.

we have had a leak a few months ago which was repaired and system pressure tested and all was well.
sadly the sight glass is dirty and we cannot see if it's clear or bubbles.

my question is what is the difference from diagnostic point of view between lack of refrigerant or a partly blocked Texv?

A partly blocked texv would also have low hP, low suction, high superheat, ?
It would almost pump down the system . Therefore liquid line temp would approach ambient temp. Pressure would approach saturation? Sub cooling would be minimal because the liquid line temp cannot drop lower than ambient?

i realise that an undersized Texv has similar systems but generally has a high liquid sub cooling as the refrigerant gets over cooled due to low flow rates.

This is could be a slightly worse case as liquid line temp is at ambient temp.

cadwaladr
30-11-2016, 07:39 AM
Get a sight glass installed asap,I take it the filter drivers have been changed and compressor oil checked .