Nitrogen refrigerator system flushing
I will explain my problem clearly and professionally.
I have a top-freezer refrigerator with a total capacity of 587 liters. Its uniqueness is that it has no air passage between the freezer and the refrigerator (it has no damper or anything). So how is it still a refrigerator? The answer is, the evaporator tubes after they pass through the freezer, the tube continues inside the back wall of the refrigerator, where there is a small fan that pushes the air into the refrigerator.
A few weeks ago I found a block of ice on the capillary in the evaporator entrance area, the evaporator itself was clean, which means there is no problem with defrosting. I defrosted it with hot air and some hot water.
After about a week I discovered that the refrigerator was not cold, the freezer was frozen, but there was no cooling in the refrigerator. A check of the fans, thermostats, etc. showed that everything was fine.
I installed a service valve on the compressor (a needle valve that fits on the copper service pipe), a gas test showed a negative condition during suction (PSI below zero about -15 -20), which means there is a gas problem. But this is not a leak, with a leak the gauge will not reach vacuum.
What did I do? In the meantime, I filled the gas to get cooling output (this is also proof that it is not a leak, at first I filled a lot of gas (according to the manufacturer's instructions 72 g R600a), I got ice up to the compressor. Then I removed the gas and left some.
The situation now, there is cooling, there is freezing, but I think the refrigerator cannot reach low temperatures because of the excess gas. Pressure in suction mode is about -10 PSI, in rest mode 4-5 PSI.
According to my suspicion, this is a soft blockage of oil or wax at the end of the capillary, which does not completely block the capillary, but causes partial flow.
Can I perform a nitrogen flush (full vacuum, then nitrogen flow through the high-pressure service valve) without opening the system, without soldering, and then "push" the oil and wax (I can also heat the end of the capillary a little), back into the filter/condenser/compressor?
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As you may or may not know, refrigeration repairs are not diy friendly, requiring advanced knowledge of refrigeration, operating pressures relative to refrigerant type, diagnosing, troubleshooting, using gauges and brazing on copper plumbing. An initial search for r600a operating pressures in refrigerators;
The evaporating pressure of R600a in refrigerators typically ranges from 0.6 to 1.0 MPa (87 to 145 psi), while the condensing pressure ranges from 2.0 to 3.0 MPa (290 to 435 psi) for optimal efficiency. These pressures can vary based on the refrigerator's design and ambient conditions.
There should be info on labeling (model, serial number, voltage, etc) along with amount of refrigerant, type, and operating pressures.
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