Wiring and plumbing diagram for 110V fridge with dual boxes

[phorvati]

Originally Posted by Richard Kollmann

If system worked before then the Capacity of TXVs are at different settings. I have designed boat holding plate Hybrid systems that way before but your unit now with only one 1/3 HP compressor will take many hours running time the first day.
So the only problem to address is the very high liquid refrigerant pressure.

Thanks, I was about to consider getting Evaporator pressure regulator. But now i realize that TXVs can be adjusted. I am ok with the system running a long time to freeze plates.

I could do a test and shut of fridge loop via fridge thermostat/solenoid and observe the low pressure. You said it should be 3-5PSI from freezer contribution alone. Then add the fridge loop and observe additional 6-10 for ideal 15PSI or less.

I think i am definitely overcharged. PSI readings dropped when I originally let out some refrigerant during the first 10 minutes. I have not really looked at the sight glass yet.

[phorvati]

Originally Posted by Coolerking

The bottom txv valve looks like the top is close to failure, when they get real rusty like that the end is near. make sure the sensing bulb is clamped to the suction line at 10 or 2 o'clock, not on the bottom.

Incomplete/partial evacuation can leave non-condensable air in the system, this will occupy the condenser and cause high pressure/ low capacity.
Are you sure you pulled a good vacuum?
I usually pull a system down for 12 hours minimum, then break the vacuum with dry nitrogen, and evac one more time to 29.9 inhg.

Richard is 100% correct, the high pressure line, after the condenser, when the boxes are cool, should not be hot at all, maybe a little warmer than ambient, but certainly not hot.

That bottom TXV was R22 from original engine drive loop which stopped working probably as far back as 2009. so that is not in the 110V loop

High pressure line after the filter and sight glass is not really hot, they are just warmer than ambient. Prior to condenser, liquid line is hot.

I purged with nitrogen prior to vacuuming. I guess now i see that a good step is to pull vacuum and then purge with nitrogen then vacuum again.

I'll see how things work and I might do that if convenient time arrives. Im running with this as we are about to go on vacation.

Suctions side was bottoming out in hg scale. I have FJC 3CFM pump and i changed the oil prior to running it.

I did add 2 packless shutoff valves on either side of the new filter/dryer element, and i have few spare filter/dryers. So i'll measure pressures after another day of run-time take the temperatures and I'll report.

[Richard Kollmann]

First let me say there are no other system in the the world that will perform the same as yours or have the same pressure readings. So no one can predict precise pressures or temperatures throughout the refrigerant cycle. The evaporator refrigerant pressure ranges for 134a refrigerant are text book correct. The 15 psi is my prediction guess of a pressure that is only sustained in a time window from 10 minutes after a warm plates start up then as the plate begin to cool where low pressure will drop. Because your eutectic plates are so large for that small compressor it may take hours before both TXVs start to see colder plate solution and begin to lower suction pressure. Eutectic plates are not as efficient as standard evaporators until sufficient ice is formed.

Now back to refrigerant volume and your eutectic holding plate system. When adding refrigerant to a one of a kind system the first time you do not want to fill reliever with liquid refrigerant to the point where sight glass is free of bubbles. What you see in sight glass will vary depending on type of glass used vertical or horizontal. My best guess is one pound of refrigerant is enough to create a differential pressure across both TXVs and create bubbles in sight glass to start system cooling. Wait till plates a completely frozen before topping off refrigerant in sight glass. A few bubbles is more efficient sometimes than a clear glass.

[phorvati]

Originally Posted by Richard Kollmann

First let me say there are no other system in the the world that will perform the same as yours or have the same pressure readings. So no one can predict precise pressures or temperatures throughout the refrigerant cycle. The evaporator refrigerant pressure ranges for 134a refrigerant are text book correct. The 15 psi is my prediction guess of a pressure that is only sustained in a time window from 10 minutes after a warm plates start up then as the plate begin to cool where low pressure will drop. Because your eutectic plates are so large for that small compressor it may take hours before both TXVs start to see colder plate solution and begin to lower suction pressure. Eutectic plates are not as efficient as standard evaporators until sufficient ice is formed.

Now back to refrigerant volume and your eutectic holding plate system. When adding refrigerant to a one of a kind system the first time you do not want to fill reliever with liquid refrigerant to the point where sight glass is free of bubbles. What you see in sight glass will vary depending on type of glass used vertical or horizontal. My best guess is one pound of refrigerant is enough to create a differential pressure across both TXVs and create bubbles in sight glass to start system cooling. Wait till plates a completely frozen before topping off refrigerant in sight glass. A few bubbles is more efficient sometimes than a clear glass.

Ok thanks. I just took another reading and low side is 15psi and high side is 145psi. And TXVs are obviously still working. I'm going to be patient with it and see how it goes.

[Richard Kollmann]

Originally Posted by phorvati

Ok thanks. I just took another reading and low side is 15psi and high side is 145psi. And TXVs are obviously still working. I'm going to be patient with it and see how it goes.

As I indicated before these systems are not always pressure/temperature predictable so I think both high and low pressures are still too high with plates having only some ice inside. No harm will come to system operating it with these pressures.

My concern is neither box will reach desired thermostat temperature setting especially if refrigerator plate is not frozen enough for thermostat to close its solenoid. We do not know what temperature the refrigerator plate will be completely frozen at. If you tap on the refrigerator plate with a small metal object and it sounds tinny it is not frozen, if the sound is rock solid it is frozen. When refrigerator plate is solid raise that thermostat temperature just high enough to close its solenoid so low pressure will drop and freeze the freezer plate.

[phorvati]

So far freezer is working good, but fridge plate has lost its frost. Its been running about 20 hours since the restart and i just went to check on it. high side is at 125 and low is at 12PSI but fridge plate is not freezing over.
I can hear the fridge solenoid hum(meaning its powered) and also I can hear refrigerant flowing inside both boxes in and around TXV area in both boxes.
The only difference so far is last night i insulated suction line outside both boxes and all the way to Condenser tray service valve. And I also insulated liquid (warm) line inside the fridge before TXV.
How do i isolate the freezer from fridge in order to troubleshoot. Freezer txv bulb is covered in frost and so is the txv itself.

[phorvati]

Scratch that, freezer stopped working as well. So something else is going on.

[Richard Kollmann]

Originally Posted by phorvati

Scratch that, freezer stopped working as well. So something else is going on.

If we ignore your report of almost normal differential pressures then the loss of adequate cooling must be do to a refrigerant leak.

[phorvati]

Originally Posted by Richard Kollmann

If we ignore your report of almost normal differential pressures then the loss of adequate cooling must be do to a refrigerant leak.

I just heated up the freezer txv on a heat gun and it started working but 10 mins later it stopped again. These TXVs were from original system. So I know there is moisture. And perhaps the fridge one has dirt since heat gun trick did not get it working. I have a brand new identical model txv which I wanted to save for engine loop. So I'll have to remove moisture.

[Richard Kollmann]

There is a difference between mechanical blockage and moisture blockage of the TXV. To tell the difference when there is no frost on valve place a rag soaked with hot water on valve. If rag sticks to valve in a few seconds and then comes off in a few minutes there is moisture in system not solids.

When you did your dehydration vacuuming were both solenoids powered to the open position?

[Coolerking]

Be careful, you can ruin the powertop on the valve if you point a hot heat gun at the sensing bulb.

Both bulbs should be individually insulated if they are not in the box they are working on.

[phorvati]

I pointed the heat gun at the bottom of the body not the top. I only have 1 solenoid and it was on.... this system has one solenoid and freezer thermostat controlls compressor while fridge tstat is wired off of condenser fan controlling solenoid. Now that I am evacuating again, and I have new txv I need to understand how to adjust them so that freezer and fridge can operate together without need to evaporator pressure regulator. U aid something along the lines of freezer should contribute 3-5psi and fridge should contribute 6-10psi.

[Richard Kollmann]

+
At this point it would be a mistake to tamper with either TXV until you clean up the probable refrigerant contamination problem. If there is moisture in refrigerant there may also be air as indicated by high side liquid pressure. Your first mistake began by replacing compressor without trying to power it up verifying the systems performance.

[phorvati]

Originally Posted by Richard Kollmann

+
At this point it would be a mistake to tamper with either TXV until you clean up the probable refrigerant contamination problem. If there is moisture in refrigerant there may also be air as indicated by high side liquid pressure. Your first mistake began by replacing compressor without trying to power it up verifying the systems performance.

Ok. So for fridge txv, there is blockage and it did not respond positively under heat meaning it's not ice. I will look for dirt in the screen. If no dirt in the screen I would like to put a new txv in its place. Is there a good writeup on testing txvs?

[Richard Kollmann]

You can test the valve settings and their flow by energizing only one solenoid at a time and monitoring system low and high pressures. WARNING DO NOT CLOSE BOTH SOLENOIDS AT THE SAME TIME AND BE READY TO STOP COMPRESSOR IF HIGH PRESSURE EXCEEDS 150PSI. Blockage of the single TXV operating will show up as very low system low pressure, 100% blockage will show a vacuum not a pressure. If it is the refrigerator TXV and refrigerator evaporator tested low correct pressure can be from 4 psi to 15 psi depending on valve size and evaporator temperature. Warm evaporator higher pressure, Cold lower pressure.