HeatingCodesMitsubishi MSZ-GL and MSY-GL mini-split blinking light codes: what each flash count means
How to count the blinks
Mitsubishi's service manual (OBH732C) says that when the indoor unit starts operating and detects an abnormality, the indoor fan motor turns off and the OPERATION INDICATOR lamp flashes. The pattern is a number of flashes, then a 2.5-second pause, then the same number again. The manual advises checking at least two consecutive cycles before you trust the count.
The normal blinking table
| Upper lamp | Abnormal point | Condition (per Mitsubishi) |
|---|---|---|
| Rapid blink, 0.5 s on, 0.5 s off | Miswiring or serial signal | The serial signal from the outdoor unit is not received for 6 minutes. |
| 2 flashes | Indoor coil thermistor or room temperature thermistor | A thermistor short or open circuit. |
| 3 flashes | Indoor fan motor | The rotational frequency feedback signal is not emitted during indoor fan operation. |
| 4 flashes | Indoor control system | The indoor control board cannot read its nonvolatile memory properly. The remedy listed is to replace the board. |
| 5 flashes | Outdoor power system | The compressor stopped three times in a row within 1 minute of starting, from overcurrent or startup failure protection. Indoor and outdoor units do not operate. |
| 6 flashes | Outdoor thermistors | Thermistor short or open circuit while the compressor is operating. |
| 7 flashes | Outdoor control system | The inverter or outdoor control board cannot read its nonvolatile memory. |
| 14 flashes or more | Other abnormality (outdoor) | An abnormality other than those above. The manual lists the stop valve and 4-way valve and says to use the outdoor failure mode recall function. |
The failure mode recall table is different
The same manual describes a "failure mode recall" function for technicians, started with the remote controller, that reads the stored fault. In that mode the indoor unit blink counts are different: 1 flash is the room temperature thermistor, 2 flashes the indoor coil thermistor, 3 flashes the serial signal, 11 flashes the indoor fan motor and 12 flashes the indoor control system. The manual itself notes that "blinking patterns of this mode differ from the ones of the troubleshooting check table."
If you see a blinking lamp on the unit with no remote involved, use the table above. If a technician has put the unit into recall mode, they will use the other table. Mixing them up is the most common way to misread a Mitsubishi blink.
What a homeowner can do
Almost every remedy in the manual involves measuring resistance, checking wiring or replacing a board. What you can do is note the exact blink count and when it happens, and check whether the outdoor unit is buried in snow or ice, which can prevent it from running correctly. For power issues, switch the unit off at the breaker for a minute and restart, but do not repeat this more than once. For a cold-weather performance question rather than a fault, see the Mitsubishi GX codes or the heating guides on this site.
Safe homeowner checks for a Mitsubishi mini-split blinking light
- Count the flashesWatch the upper OPERATION INDICATOR lamp for at least two cycles and write down the count.
- Check the outdoor unitMake sure the outdoor unit is not buried in snow or blocked by ice or debris. Clear it gently by hand and keep the air flow open.
- Restart onceTurn the unit off at the remote, wait a minute, and restart. If you use the breaker, turn it off for about a minute and back on.
- Call an HVAC technicianGive them the model number and the blink count.
Frequently asked questions
Which lamp do I count?
The manual refers to the upper lamp of the OPERATION INDICATOR on the indoor unit.
Does this apply to every Mitsubishi mini-split?
No. It is from the service manual for MSZ-GL06 to GL24 and MSY-GL09 to GL24 wall-mounted indoor units. Other series, such as the GX and FH lines, have their own tables.
What does 2 flashes mean?
In the normal table, 2 flashes is an indoor coil or room temperature thermistor problem. In the recall table, 2 flashes is the indoor coil thermistor only.
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.
Safety note: this page is general information drawn from the sources above. Gas, combustion and line-voltage repairs belong to a licensed professional. Your own equipment's label and manual take priority over anything here. Read the full disclaimer.