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Mitsubishi LED 17 blinks: refrigerant system abnormality

By How House Works EditorialBased on Mitsubishi Electric manualsChecked against sources Updated

Mitsubishi Electric display

LED 17 blinks

“Outdoor refrigerant system abnormality”

GL, FS, FH, GS06–24, GS30/36 · MUZ-GL Outdoor Service Manual OBH733J, p. 46; MUZ-FS Outdoor Service Manual OBH873B, p. 30; MUZ-FH Outdoor Service Manual OBH684E, p. 34; MUZ-GS Outdoor Service Manual OBH875B, p. 64
Technician

Outdoor board LED, table 10-3. The outdoor unit does not operate. Condition: “A closed valve and air trapped in the refrigerant circuit are detected based on the temperature sensed by the indoor and outdoor thermistors and the current of the compressor.” The remedy starts with a check for a gas leak in the connecting piping. The “Check of outdoor refrigerant circuit” procedure in all four outdoor manuals prints “CAUTION : Do not start the operation again to prevent hazards.” (MUZ-GL Outdoor Service Manual OBH733J, p. 59; MUZ-FS Outdoor Service Manual OBH873B, p. 42; MUZ-FH Outdoor Service Manual OBH684E, p. 46; MUZ-GS Outdoor Service Manual OBH875B, p. 79).

What it means

Seventeen blinks after each 2.5-second pause comes from the LED on the outdoor unit’s inverter P.C. board, not from the indoor lamp. That LED stays lit in normal operation and shows a code as a number of blinks after each 2.5-second off period MUZ-GL Outdoor Service Manual OBH733J, p. 46. Table 10-3 calls 17 blinks “Outdoor refrigerant system abnormality” in the GL, FS, FH and GS outdoor manuals, and the outdoor unit does not operate MUZ-GL Outdoor Service Manual OBH733J, p. 46; MUZ-FS Outdoor Service Manual OBH873B, p. 30; MUZ-FH Outdoor Service Manual OBH684E, p. 34; MUZ-GS Outdoor Service Manual OBH875B, p. 64. The unit sets it when the indoor and outdoor thermistor readings and the compressor current point to a closed valve and air trapped in the refrigerant circuit.

What the indoor lamp shows:

  • In normal operation, the indoor lamp tables have no 17-blink row. Their “14 blinks or more” row, “Other abnormality”, sends the technician to the stop valve, the 4-way valve and the outdoor unit’s failure mode recall MSZ-GL Indoor Service Manual OBH732D, p. 27. The manuals do not say which indoor pattern goes with LED 17.
  • In failure mode recall, a technician’s procedure, the FH table shows this fault as 14 or more blinks of the indoor lamp with the outdoor LED at 17 MUZ-FH Outdoor Service Manual OBH684E, p. 33. The GL, FS and GS recall tables show it as 16 blinks of the indoor lamp with the outdoor LED at 1 MUZ-GL Outdoor Service Manual OBH733J, p. 45; MUZ-FS Outdoor Service Manual OBH873B, p. 29; MUZ-GS Outdoor Service Manual OBH875B, p. 63. The manuals note that recall patterns differ from table 10-3, so a single LED blink in recall is not one of the 1-blink rows of that table.

Check these first

The LED sits on a board in the outdoor unit, and the owner’s manuals say the user should not disassemble, alter or repair the unit MSZ-GL Operating Instructions, p. En-1. What the owner’s manuals do give:

  1. Stop the unit with the remote and consult your dealer. The owner’s manuals list a blinking operation indicator lamp and any refrigerant leakage you find as reasons to stop using it MSZ-GL Operating Instructions, p. En-11; MSZ-FH Operating Instructions, p. En-12.
  2. If the unit no longer cools or heats, the manuals say refrigerant may be leaking and to consult your dealer. Leaking refrigerant that touches a heat source such as a fan heater, kerosene heater or cooking stove creates a harmful gas MSZ-GL Operating Instructions, p. En-1.
  3. Do not switch the breaker off and on while the unit runs; the owner’s manuals warn of sparks and fire. Switch it off with the remote first MSZ-GL Operating Instructions, p. En-1.

Among the outdoor-unit symptoms the owner’s manuals explain are white “smoke” in heating, which is vapor from defrosting, and water dripping from the outdoor unit, from condensation or melting ice MSZ-GL Operating Instructions, p. En-11.

When to call a licensed technician

  • The table’s remedy: check for a gas leak in the connecting piping, check the stop valve, and follow “Check of outdoor refrigerant circuit” in section 10-5 MUZ-GL Outdoor Service Manual OBH733J, p. 46.
  • In all four outdoor manuals one branch of that check says the operation has stopped to prevent the diesel explosion caused by air trapped in the refrigerant circuit, and ends with “CAUTION : Do not start the operation again to prevent hazards.” MUZ-GL Outdoor Service Manual OBH733J, p. 59; MUZ-FS Outdoor Service Manual OBH873B, p. 42; MUZ-FH Outdoor Service Manual OBH684E, p. 46; MUZ-GS Outdoor Service Manual OBH875B, p. 79. FS and GS print the same warning in the recall row for this fault as well MUZ-FS Outdoor Service Manual OBH873B, p. 29; MUZ-GS Outdoor Service Manual OBH875B, p. 63.
  • The service manuals warn that when a valve is opened or closed below freezing temperatures, refrigerant may spurt out and cause injuries, and they say never to use any refrigerant other than the one specified MUZ-GL Outdoor Service Manual OBH733J, p. 2.
  • If a repair involves recharging the unit with refrigerant, the owner’s manuals say to ask the service technician for details MSZ-GL Operating Instructions, p. En-1. Refrigerant work is for a technician certified under EPA Section 608.

Notes for different models

  • FH recall mode groups the stop valve, 4-way valve and refrigerant system faults under “14 blinks or more” of the indoor lamp; GL, FS and GS use 14 for the first two and 16 for the refrigerant system MUZ-FH Outdoor Service Manual OBH684E, p. 33; MUZ-GL Outdoor Service Manual OBH733J, p. 45.

Related Mitsubishi Electric codes

See also

Other ductless mini-splits: Daikin, Fujitsu, MrCool

All Mitsubishi Electric codes

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Sources

  1. Mitsubishi Electric Corporation. MSZ-GL Indoor Service Manual OBH732D. No. OBH732, Revised Edition-D, issued Feb. 2022; covers MSZ-GL06–24NA and MSY-GL09–24NA. Accessed Oct 12, 2026.
  2. Mitsubishi Electric Corporation. MUZ-GL Outdoor Service Manual OBH733J. No. OBH733, Revised Edition-J, issued Jun. 2021; covers MUZ-GL09–24NA and NAH, MUY-GL09–24NA (the cover lists no MUZ-GL06). Copy hosted by a Mitsubishi distributor (Gemaire/Baker Distributing).. Accessed Oct 12, 2026.
  3. Mitsubishi Electric Corporation. MUZ-FS Outdoor Service Manual OBH873B. No. OBH873, Revised Edition-B, issued Aug. 2021; covers MUZ-FS06–18NA and NAH. Accessed Oct 12, 2026.
  4. Mitsubishi Electric Corporation. MUZ-FH Outdoor Service Manual OBH684E. No. OBH684, Revised Edition-E, issued Jun. 2021; covers MUZ-FH06–18NA and NAH. Copy hosted by a Mitsubishi distributor (Gemaire).. Accessed Oct 12, 2026.
  5. Mitsubishi Electric Corporation. MUZ-GS Outdoor Service Manual OBH875B. No. OBH875, Revised Edition-B, issued Oct. 2022; covers MUZ-GS NA, NAH and NAHZ, MUY-GS NA, and the GS30/36 NA2 and NAH2 outdoor units. Copy hosted by a Mitsubishi distributor (Meier Supply).. Accessed Oct 12, 2026.
  6. Mitsubishi Electric. MSZ-GL Operating Instructions. Printed code DG79A01LH01 (the file name says JG79Y190H02); no publication date printed; covers MSZ-GL06/09/12/15NA and MSY-GL09/12/15NA; English pages are numbered En-1 onward. Accessed Oct 12, 2026.
  7. Mitsubishi Electric. MSZ-FH Operating Instructions. Printed code JG79A806H05, layout date 2019/06/27; a newer revision may exist on Mitsubishi's MyLinkDrive portal (not checked); covers MSZ-FH06/09/12/15/18NA and MSZ-FH18NA2; English pages are numbered En-1 onward. Copy hosted by a Mitsubishi distributor (Meier Supply).. Accessed Oct 12, 2026.