HeatingCodesMitsubishi MSZ/MSY-GL blinking light codes
On these Mitsubishi indoor units the OPERATION INDICATOR lamp blinks when the unit detects a fault. The number of flashes in each cycle tells you which area has the problem.
How to read the display
Count the flashes of the upper lamp of the OPERATION INDICATOR. A steady rapid blink (on 0.5 seconds, off 0.5 seconds) is one pattern. The numbered patterns flash that many times and then stay off for 2.5 seconds before repeating. The manual says to check at least two consecutive cycles to be sure of the count.
The manual also describes a "failure mode recall" function, run with the remote and the emergency operation switch, that reports the stored fault with a different numbering (1, 2, 3, 11 and 12 flashes for the indoor unit). Those numbers do not match this table, and the manual warns of exactly that. The table below is the one for the lamp as it normally blinks.
Mitsubishi code table
| Code | Meaning | What the document says |
|---|---|---|
| Rapid blink (0.5 s on, 0.5 s off) | Miswiring or serial signal problem between indoor and outdoor unit | The condition is that the serial signal from the outdoor unit is not received for 6 minutes. Full explanation |
| 2 flashes | Indoor coil or room temperature thermistor short or open circuit | Full explanation |
| 3 flashes | Indoor fan motor: no rotational frequency feedback signal during indoor fan operation | Full explanation |
| 4 flashes | Indoor unit control system: cannot properly read data in the nonvolatile memory of the indoor control board | The remedy is to replace the indoor electronic control board. |
| 5 flashes | Outdoor power system: compressor stopped three times consecutively within 1 minute of startup from overcurrent or startup failure protection | Indoor and outdoor units do not operate. Check the stop valve (technician work). |
| 6 flashes | Outdoor thermistors short or open during compressor operation | |
| 7 flashes | Outdoor control system: cannot properly read data in the nonvolatile memory of the inverter or outdoor control board | |
| 14 flashes or more | Other outdoor unit abnormality | The manual lists checking the stop valve and the 4-way valve, and using the outdoor unit failure mode recall for details. |
Source: Mitsubishi OBH732C, 9-4 Troubleshooting check table (indicator lamp column) and 9-3 flow chart.
Detailed explanations
Sources
- Service Manual OBH732 Revised edition-C: MSZ-GL06NA to MSZ-GL24NA and MSY-GL09NA to MSY-GL24NA, Operation Indicator and Failure Mode Recall (Mitsubishi Electric (copy hosted by distributor Total Comfort Mechanical)) Covers: Mitsubishi MSZ-GL and MSY-GL wall-mounted indoor units (06 to 24 sizes) as listed in the manual. Other Mitsubishi lines (for example the GX/FH series) have their own tables.