R-Pro › Field cases › Air conditioning
Flare Joint Refrigerant Leak — refrigerant leaking at pipe connection
Likely causes
Flare nut undertightened — below specified torque
Check: Scan all flare joints with electronic leak detector (sensitivity ≤0.1 g/yr). Apply soap bubbles for large leaks. Monitor low-side gauge for leak rate
What to do: Re-torque with torque wrench — Ø6.35: 14–18 N·m / Ø9.52: 34–42 N·m / Ø12.7: 49–61 N·m → after re-torquing, nitrogen pressure test (1.5 MPa, 24 h) to confirm no further leak
Flare face scratched or angle defective — poor seating causes leak
Check: Disconnect nut and inspect flare face visually and by touch — check for copper chips, scratches, oval deformation. Measure angle with gauge to confirm within ±2° of 45°
What to do: Cut off existing flare and re-flare → for R-410A/R-32 high-pressure refrigerants, use double flare or union fitting → re-torque to spec → pressure test
Nut loosened by vibration or repeated shock
Check: Check outdoor unit for vibration, then test flare nut by hand for play. Inspect pipe support clamp spacing and fixing condition
What to do: Re-torque to spec → secure additional pipe clamps at max 1.5 m intervals → install anti-vibration pads under outdoor unit feet to isolate vibration
No torque wrench: fully hand-tighten then add 1/6–1/4 turn with spanner. This is only a stopgap — proper torque wrench is always required.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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