Troubleshooting Fujitsu 10-3 Compressor Temperature Error

Error Description

The 10-3 error (Compressor Temperature Error) indicates that the compressor casing temperature is too high. This safety protection prevents damage to the compressor. The error code appears on the indoor unit via indicator lights.

How to Read the Error Code on the Indoor Unit

The indoor unit displays errors using three indicator lights:

• Operation
• Timer
• Economy (typically flashes rapidly during an error)

To determine the code:

1. Count the flashes on each light separately.
2. Note the number of flashes for the Operation light.
3. Note the number of flashes for the Timer light.

Error Code Combinations by Model

10 flashes Operation + 3 flashes Timer RL2 series, RLS3 series, RLS2 series, RLB/RLXB series, RLF series, RLF1 series, LUAS1 series, LMAS series, LZBS series, LZAS series, LPAS series, RGLX series, RLE series.

3 flashes Operation + 8 flashes Timer RLS series, RLXS series, CQ series, RQ series, R2 series, RL series, RML series, RMLQ series, CLX series, CLX1 series, RLX series, RLXQ series, CL1 series, CL series, RLQ series. (Note: Operation and Timer LED colors are reversed on these models. Refer to the wired remote controller for confirmation.)

Continuous flash Operation + 8 flashes Timer ABU18RULX, ABU24RULX, ABU36RSLX.

10 flashes LED A + 3 flashes LED B + 1 flash LED F AOU36RLXFZH, AOU45RLXFZ.

2 flashes Power Mode LED + Solid Error LED + 10 flashes L1 + 3 flashes L2 + Solid L5 + Solid L6 AOU30RLXEH.

EA31 on Outdoor LED AOU48RLXFZ, AOU48RLXFZ1.

97 / 98 / 1B on Wired Remote UTY-RNBYU, UTY-RNNUM, UTY-RVNUM, UTY-RSNUM, UTY-DMMUM, UTY-RNRUZ series, UTY-RSRY, UTY-RHRY.

Common Causes

The most frequent causes are issues with the Electronic Expansion Valve (EEV) or incorrect system refrigerant charge. Other possibilities include restricted flow (clogged strainer), poor condenser airflow, or a faulty compressor thermistor.

Troubleshooting Checklist

Cooling Operation

1. Check the 3-way valve (gas side) — Ensure it is fully open. If it was closed, open it and test system operation.
2. Inspect the EEV — Verify the Electronic Expansion Valve is functioning correctly. Replace if defective.
3. Check the strainer — Inspect for clogs. There should be little to no temperature difference between the strainer inlet and outlet. A noticeable temperature difference indicates a clog — replace the strainer.
4. Inspect the condenser fan motor:
   • Confirm the fan spins freely with minimal resistance.
   • Ohm the motor windings. Replace the motor if readings are out of specification.
5. Test the Compressor Thermistor — Measure resistance and compare to the thermistor resistance chart (refer to the service manual for your model).
6. Check for refrigerant leaks — If the above steps do not resolve the error, perform a thorough leak check, repair any leaks, and recharge the system to the correct amount.

Heating Operation

1. Check the 3-way valve (liquid side) — Ensure it is fully open. If closed, open it and test operation.
2. Inspect the EEV — Verify the Electronic Expansion Valve is operating correctly. Replace if defective.
3. Check the strainer — Same procedure as in Cooling: no temperature difference between inlet and outlet. Replace if clogged.
4. Continue with steps 4–6 from the Cooling Operation checklist (condenser fan, compressor thermistor, and leak check).

Additional Recommendations

• Always refer to the specific service manual for your model for wiring diagrams, component specifications, and thermistor charts.
• Use proper safety precautions and appropriate gauges/manifolds when working with refrigerant.
• If the error persists after completing the checklist, the compressor itself may be failing or there could be a control board issue — contact Fujitsu technical support or a certified technician.

This structured guide should help technicians quickly diagnose and resolve the 10-3 Compressor Temperature Error on Fujitsu mini-split systems. Let me know if you need any sections expanded, images added, or a downloadable version (e.g., PDF or Word doc).