Clear sightglass. Vapor or liquid?

[Sparkplug]

Walk in freezer, -16 degrees F each morning ,after the door has been locked closed for 15 hours overnight, each night.

No complaints, just a preventive measurement on a system that has been repaired in the past. Past repair types are unknown.

Copeland semi-hermetic compressor. Good airflow over condenser and evap. Subcool 5 degrees at the receiver, superheat 46 at the compressor (suction lines are insulated). Sightglass mounted 2 ft after the receiver, is clear. Would you assume it is full of vapor or liquid?

Evap superheat unknown, but am getting 5 degree air cooling over evap coil.

Frost occurs up the compressor on suction lines, but stops near the compressor inlet.

[chemi-cool]

Would it work so good if it was only vapour?

If you look close, you can see that liquid works a bit like magnified glass.

Chemi

[Sparkplug]

Maybe the morning temp of -16F just 'sounds' good. Maybe it takes 12 hours to achieve that temp every day. Maybe the tev is running full throttle all the time. Maybe the compressor rarely shuts off and runs all night. Maybe the compressor is running hotter than it could be running.

These are the things I don't know the answer to. That is why I look for a second opinion on the high superheat and low subcool. Actually, I think my gauge may be off 2 degrees. If so, then the subcool is actually 3 degrees. But I posted the stats here as I recorded them at the time of reading. I think the amp rating was 10.x amps full load, and I measured 9.x amps on each of two legs of the compressor.

All the figures seem to add up to a 'close call'. I don't have enought experience on my own, to make the call. In my mind, I think that sightglass was empty, but I just don't know.

[Andy W]

In my mind, I think that sightglass was empty, but I just don't know.

Close the reciever service valeve and start to pump it down, after a short while you will see the glass start to empty, then open the receiver valve and the glass should fill before your very eyes, either do that or you could crack a flare nut off for a split second to prove that you have liquid at various points of the circuit, that is how we used to do it before all the environmental policies and legislation laws came into force, should not be difficult to prove that you have liquid.

[afeef]

hi
the tev is not properly manage the flow of refrigerant,,
there is some reasons i gess:
- the bulb is not fixed properly to suction line
- there is partial bloackage on the orifice of tev
-the needle of tev is stuck
you will need to clean the tev with proper solution
and is better to change the oil of compressor ,,if it is more than 4 years not be changed
the dirty oil make the tev stuck and not operate well
lot of thanks
afeef

[Sparkplug]

Thanks guys. Today I took a close look at the glass. By golly, it did in fact magnify my fingertips, to where I could make out my finger prints. I like that new trick!

And I closed the service valve and then saw bubbles, so I know the glass is full.

Unfortunately, the freezer began losing 4 degrees a day since about 2 weeks ago. Down to -12f instead of -16 that is has been getting for the last 10 weeks.

But at least I know the glass is full. Thanks all!