Fujitsu ARU12RLF 12,000 BTU Ceiling Cassette Mini Split, 24 x 24 in, Quiet Operation MECH-LEAK Error Fix: Refrigerant Leak — Indoor Coil or Line Set

Error code MECH-LEAK on the Fujitsu ARU12RLF 12,000 BTU Ceiling Cassette Mini Split, 24 x 24 in, Quiet Operation means: Refrigerant Leak — Indoor Coil or Line Set. Refrigerant is leaking from the system causing gradual performance loss — Fujitsu mini-splits are known for pinhole leaks in indoor evaporator coils, particularly on 12,000 BTU models; flare fitting leaks at the line set connections are also common, especially if the installation was not properly torqued; symptoms include reduced cooling/heating capacity, ice forming on the indoor coil, and hissing sounds near connections; a proper leak search requires pressurizing the system with dry nitrogen and using an electronic leak detector; DO NOT simply recharge without finding and fixing the leak

The most successful fix is "Perform Leak Detection and Repair Indoor Coil or Line Set Leak" (hard difficulty, ~120 minutes). This fix costs nothing. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Perform Leak Detection and Repair Indoor Coil or Line Set Leak") is rated hard difficulty and takes about 120 minutes. Tools needed: Electronic leak detector, Nitrogen tank with regulator, Vacuum pump, Brazing torch, Adjustable wrenches.

DIY cost: $0. Professional repair typically costs $300-$600. Many homeowners save money by trying the top-ranked community fix first.

The Fujitsu ARU12RLF 12,000 BTU Ceiling Cassette Mini Split, 24 x 24 in, Quiet Operation has 8 other known error codes, including: 01 (Indoor Unit PCB Error), 02 (Communication Error — Indoor to Outdoor Unit), 03 (Communication Error — Remote Controller to Indoor Unit), 04 (Outdoor Unit PCB Error), 05 (Outdoor DC Fan Motor Open/Short Circuit), and 3 more.

Error code MECH-LEAK also appears on 8 other Fujitsu models: 12,000 BTU 18 SEER Slim Duct Mini Split, 8 in Height, Quiet Operation, 12,000 BTU 25 SEER Halcyon Wall-Mount Mini Split with WiFi Control, 15,000 BTU 25 SEER Halcyon Wall-Mount Mini Split with Energy Saving Mode, 24,000 BTU 19 SEER Wall-Mount Mini Split with Low Ambient Cooling, 36,000 BTU 18 SEER Multi-Zone Heat Pump Outdoor Unit, 48,000 BTU Multi-Zone Heat Pump Outdoor Unit, and 2 more. The fix may vary by model, so check each model's specific page for tailored repair steps.