Pressure pattern
Low side fell to about -20 psi
The negative suction pressure made a restriction or partially closed joint more coherent than a normal charge condition.
Confirmed sealed-system case · LG
A Line That Passed Nitrogen Still Had an Oil Restriction
The low side pulled to -20 psi after compressor replacement. Opening the return and capillary path exposed enough trapped oil to explain why separate flow checks had looked better than the assembled system behaved.
What the source establishes
- A 1706 compressor had just been installed on an LG LMXS27626D/01.
- The reported pressures were about -20 psi low side and 90-95 psi high side after a weighed charge.
- The capillary tube and condenser appeared to pass nitrogen when checked separately.
- After the return and capillary were disconnected, a nitrogen purge pushed a large amount of oil from the return.
- The refrigerator began working after that purge.
A similar symptom can have a different cause on another appliance or model.
How the evidence narrowed the diagnosis
Initial check
Separate components passed nitrogen
That did not reproduce the complete assembled path or show how much oil remained in it.
Physical finding
The purge moved substantial oil
Oil emerged from the return after the capillary and return were opened and nitrogen was applied.
Possible origin
The system had reportedly run open for several days
The technician suspected that the customer's removal of a diagnostic piercing valve contributed to the oil problem. The discussion did not prove that causal link separately.
What the evidence supports
The explicit oil discharge and return to operation support an oil-related restriction in the sealed-system path after compressor replacement. The case also shows why a line that passes some nitrogen is not necessarily unrestricted in its assembled operating condition.
This is a post-repair finding, not a recommendation to infer restriction from pressure alone.
Operation returned after the oil was purged
The technician reported that the refrigerator began working after nitrogen pushed a large amount of oil from the return path.
What should be verified next
Preserve the exact pressure pattern, charge weight, joints disturbed and direction of each flow test. A sealed-system technician should verify the complete path and final operating temperatures rather than stopping at a partial nitrogen-flow check.
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Refrigerant and pressure safety: brazing, nitrogen purging, evacuation and charging require qualified sealed-system service, regulated handling and model-specific procedures.
A replacement that did not solve the fault
A repair that did not follow the obvious path
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