Fujitsu AOU18RLXFZH 18,000 BTU Multi-Zone Mini Split System with Inverter Compressor 73 Error Fix: High Pressure Protection

Error code 73 on the Fujitsu AOU18RLXFZH 18,000 BTU Multi-Zone Mini Split System with Inverter Compressor means: High Pressure Protection. The high-pressure switch has tripped or the discharge pressure has exceeded the safe limit — the most common causes are a dirty outdoor coil (blocking airflow), outdoor fan motor failure, refrigerant overcharge, a non-condensable gas (air) in the system, or extremely high outdoor ambient temperature; clean the outdoor coil with a coil cleaner and garden hose (fin-side out); verify the outdoor fan is running at full speed; check refrigerant charge

The most successful fix is "Test High-Pressure Switch and Remove Non-Condensables" (hard difficulty, ~90 minutes). Estimated DIY cost: $10-$30. 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 ("Test High-Pressure Switch and Remove Non-Condensables") is rated hard difficulty and takes about 90 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Vacuum pump, Manifold gauge set, Refrigerant recovery machine.

DIY cost: $10-$30. Professional repair typically costs $150-$220. Many homeowners save money by trying the top-ranked community fix first.

The Fujitsu AOU18RLXFZH 18,000 BTU Multi-Zone Mini Split System with Inverter Compressor 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 73 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.