Mitsubishi Electric City Multi aircon 4255 error code
Use this Mitsubishi Electric City Multi 4255 error code guide to decide when to stop resetting, what to capture, and what to check before parts are quoted.
What does Mitsubishi Electric 4255 mean?
Mitsubishi Electric City Multi 4255 is listed as overcurrent caused by a short-circuited motor in VRF rows such as City Multi VRF outdoor-unit diagnostics. The loaded row is source-backed by official diagnostic material. Confirm the exact model, series, or signal row before accepting a parts quote.
Compressor start, lock, overcurrent, overload, or inverter-drive protection.
Power-module, IPM, voltage, or wiring fault affecting compressor drive.
Compressor mechanical or winding issue after electrical checks are confirmed.
What to do now
Use these steps before another reset or parts quote.
Stop using the unit if 4255 returns
Stop repeated restarts if 4255 returns; compressor and inverter faults can become more expensive when forced to run.
Reset 4255 once
Capture the 4255 display, then reset once only if there is no burning smell, repeated trip, or hot outdoor unit.
Send these to us
4255 error code, a clear display photo, Mitsubishi Electric City Multi model stickers, affected rooms, reset result, and trip timing and outdoor-unit behaviour
Source-specific guidance
These diagnostic-reference notes help match the code to the exact model. Electrical, refrigerant, wiring, resistance, and component checks are technician work, not DIY steps.
| Source detail | What it says |
|---|---|
| Source repair action | Check the inverter, compressor, IGBT, fan inverter board, outdoor fan, and outdoor model-selection switch settings. |
| Singapore / model note | Official Mitsubishi Electric Singapore City Multi PDF page 4, primary fault-code table for the outdoor unit. Confirm the installed City Multi equipment and the unit reporting the code before parts replacement. The table also shows preliminary code 4355 in parentheses; it is diagnostic context, not a separate public fault route. |
What to check before repair
Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.
| You can check | Technician should confirm |
|---|---|
| Before resetting 4255, take a clear display photo. | Confirm whether 4255 is compressor start, overload, lock, or drive protection. |
| Capture the Mitsubishi Electric City Multi indoor and outdoor model stickers so the correct family row is used. | Check supply voltage, inverter output, IPM status, compressor current, and winding readings. |
| Note whether one room, several rooms, or the whole system is affected, plus whether it returns after one reset. | Review trip history and compressor mechanical signs before quoting replacement. |
What changes the next step
These clues decide whether the first check is room-side, shared outdoor-side, refrigerant-side, source-table, or model-family confirmation.
| What you see | What it points to |
|---|---|
| Only one indoor unit shows 4255. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same 4255 fault. | The shared outdoor side, power path, communication trunk, or refrigerant circuit needs priority checking. |
| The outdoor unit hums, starts briefly, or trips soon after startup. | Power, inverter, IPM, compressor current, and winding checks decide the repair path. |
| The model family is different from the row you found online. | Use the model or series filter first; same-looking codes can still belong to different diagnostic tables. |
| The model belongs to VRF rows such as City Multi VRF outdoor-unit diagnostics. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
Compressor drive or replacement decision
Mitsubishi Electric City Multi 4255 can still be a repair if power, inverter, or module checks find the cause. Compressor replacement should be weighed against age, warranty, and the rest of the system condition.
Inverter or IPM faults are not the same as confirmed compressor mechanical failure.
Compressor winding and current readings should be measured before replacement is discussed.
Older systems need a repair-versus-replace check if compressor-side parts are expensive.
Mitsubishi Electric 4255 questions
What does the Mitsubishi Electric 4255 error mean?
Can I fix a Mitsubishi Electric 4255 error myself?
Is it safe to keep running the aircon with a 4255 error?
What causes a Mitsubishi Electric 4255 error?
Will a Mitsubishi Electric 4255 error need a repair or a full replacement?
What should I send a technician about a Mitsubishi Electric 4255 error?
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