The blinking lamps
Fujitsu mini split error codes
and what the flashes mean
A Fujitsu wall unit flashes its code on two lamps instead of printing it. The green OPERATION lamp gives the first digit, the orange TIMER lamp the second, and the green ECONOMY lamp flashes the whole time, so 4 flashes and then 1 is code 41. A wired remote shows the number.
ASU9, ASU12 and ASU15RLS3 wall units: the flash codes
Read from Fujitsu’s service instructions for these three models. Other Fujitsu lines have their own manuals, so match the model on your unit’s label first.
Fujitsu ASU RLS3 wall unit flash codes| Code | Flashes: OPERATION, then TIMER | What it means | What it usually takes |
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| 11 | 1 and 1 | The indoor and outdoor units aren’t communicating | The wiring between the units, or a board |
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| 41 | 4 and 1 | Room temperature sensor (thermistor) fault | An indoor sensor |
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| 42 | 4 and 2 | Indoor coil (pipe) temperature sensor fault | An indoor sensor |
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| 51 | 5 and 1 | Indoor fan motor fault | The fan motor, or a blower wheel that’s dragging |
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| 62 | 6 and 2 | Outdoor main control board fault | An outdoor board |
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| 65 | 6 and 5 | Inverter power module (IPM) fault | The outdoor inverter board |
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| 71 | 7 and 1 | Discharge temperature sensor fault | An outdoor sensor |
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| 74 | 7 and 4 | Outdoor temperature sensor fault | An outdoor sensor |
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| 94 | 9 and 4 | Overcurrent: the system shut down on too much current | The power side or the compressor, tested before anything is ordered |
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| 95 | 9 and 5 | Compressor control fault | The compressor or the board that runs it |
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| 97 | 9 and 7 | Outdoor fan motor fault | The outdoor fan motor |
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| 99 | 9 and 9 | Reversing valve (4-way valve) fault | The valve that switches the system between heating and cooling |
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| A1 | 10 and 1 | Discharge temperature fault | The refrigerant side of the outdoor unit |
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Source: Fujitsu ASU9RLS3 service instructions. Codes vary by model and control board: the chart printed on your unit, or its manual, is the final word.
Normal, or time to call? What Fujitsu’s manual says
Fujitsu ASU RLS3: normal operation or a reason to call| What you see | What it means | What to do |
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| OPERATION lamp blinking in heat mode, the unit paused | Defrost: the outdoor coil is melting off its frost, for up to 15 minutes | Nothing. It picks back up on its own. |
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| OPERATION and TIMER blinking, ECONOMY blinking fast | A fault code | Count the flashes, turn off the breaker, and call. That’s Fujitsu’s own instruction. |
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| Water leaking from the indoor unit | Fujitsu lists it as a reason to stop the unit | Turn it off and call. It’s usually the drain. |
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Source: Fujitsu ASU9RLS3 operation manual. Codes vary by model and control board: the chart printed on your unit, or its manual, is the final word.