HVACopediaFujitsu · Heat pump
Outdoor LED1 18 flashes High discharge temperature (outdoor board LED)
What the control is telling you
Multi-zone 18/24 outdoor board: LED1 flashes 18 times while the other LEDs stay off. Same fault family as indoor code A1. The LEDs sit on the back side of the board and are seen through a hole.
Applies to: Fujitsu 18 type (2-zone) and 24 type (3-zone) multi outdoor units
Likely causes
- Low refrigerant charge / leak
- Restriction or EEV fault
- Blocked outdoor coil
- Discharge thermistor misreading
Test and repair steps
- Look at the outdoor PCB LEDs (rear of the board, viewed through the hole) and count the flashes on each LED.
- Then follow the checks for indoor code A1: Check for leaks and correct charge.
- Check EEV operation and for restrictions.
- Clean outdoor coil and check airflow.
Settings for these units
Operating range and service space · Fujitsu multi-zone outdoor 18/24 type
| Item | Value |
|---|---|
| Cooling outdoor range | 14 to 115 F DB |
| Heating outdoor range | 5 to 75 F DB |
| Cooling indoor range | 65 to 90 F DB |
| Heating indoor range | 60 to 88 F DB |
| Rear (open top, rear wall only) | 4 in. or more |
| Rear + sides | 4 in. rear, 10 in. sides |
| Front wall only | 24 in. or more |
| Between side-by-side units | 10 in. or more |
| Base height | 2 in. or more above floor |
Unit tilt no more than 3 degrees and never toward the compressor side.
Below 32 F outdoor do not fit the drain pipe/caps (freezing).
Other codes on the same units
- Outdoor LED1 13 flashes Compressor rotor position detection error (outdoor board LED)
- Outdoor LED1 14 flashes Trip terminal L error (outdoor board LED)
- Outdoor LED1 15 flashes Outdoor fan motor error (outdoor board LED)
- Outdoor LED1 17 flashes Outdoor PCB micro communication error (outdoor board LED)
- Outdoor LED1 19 flashes High compressor temperature (outdoor board LED)
- Outdoor LED1 2 flashes Discharge temperature sensor error (outdoor board LED)
- Outdoor LED1 20 flashes 4-way valve error (outdoor board LED)
- Outdoor LED1 21 flashes Outdoor PCB model information error (outdoor board LED)
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Source: Fujitsu Outdoor unit 18-24 type (North American trilingual) installation P-N 9374747160.pdf - section 8.2 Outdoor unit LED. Summarized in our own words; check the original manual for your model.
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