Error codes and blinking lights: what an Indian split AC is telling you

Updated September 14, 2026 · Claude AC · 2 sources cited

Contents (7)

Why there is no national list of AC error codes
Getting the code out of the machine
The family a code belongs to
What to check before you call
The code is not the diagnosis
The codes that only appear in July
Frequently asked questions

The machine stops, two characters appear on the indoor display, or a small green light under the flap begins flashing in a pattern. Within a minute most owners are typing that code into a search engine along with the brand name, and finding three lists that disagree with each other. Understanding why they disagree is the most useful thing on this page, because it changes what you should do next.

Why there is no national list of AC error codes

Indian regulation covers a great deal of what a split air conditioner does. IS 1391 (Part 2), the Bureau of Indian Standards specification for split air conditioners, sets construction, safety and performance requirements and the test procedures behind them. The BEE star label standardises how seasonal efficiency is declared, as our guide to BEE star ratings and ISEER explains. Neither says anything at all about diagnostics.

Fault codes are a service tool. Each manufacturer writes its own, for its own technicians, and changes them between product generations of the same brand. The consequence is blunt: a table promising that a given code « means low voltage » is guessing, and on the machine hanging in your bedroom those same two characters may point to a sensor circuit, a communication failure, or nothing that applies to your model year at all.

Three sources are authoritative, in this order: the manual that came in the carton, the service sticker inside the indoor unit’s front flap or on the outdoor casing, and the brand’s own support line quoting your model number. Photograph that sticker and the model plate once, today, and keep the photo. It costs nothing and it is the difference between a diagnosis and a debate.

Getting the code out of the machine

Indian splits report faults in one of three ways.

A digital display on the indoor unit shows the code directly. Write down every character, including letters, a leading zero, and whether it alternates with the temperature.
Blink codes. Units without a display flash the run, timer or defrost LEDs in a counted pattern: a group of flashes, a pause, then the same group again. Count it twice and note which LED is flashing — many brands encode two halves of one code across two lamps.
A self-diagnosis mode reached from the remote, in which the unit replays its last stored fault. The key sequence is model-specific and lives in the manual, whatever a video may promise.

Record the conditions alongside the code, because they carry as much information as the code itself: does it appear at start-up or after twenty minutes of running, only on hot afternoons or only at night, with the outdoor fan turning or with it dead, during heavy rain or in dry heat. A technician who arrives with that sentence in hand is diagnosing; one who arrives with only two characters is guessing at your expense.

The family a code belongs to

Codes are not standardised, but the underlying fault families are, because every inverter split protects itself against the same short list of conditions. Knowing which family you are in tells you whether this is a twenty-minute fix or a service visit.

Fault family	What the machine detected	What it usually is, in Indian conditions	Owner-fixable?
High pressure or discharge temperature	The condenser cannot reject heat fast enough	A choked outdoor coil, a boxed-in balcony recirculating hot air, or a stopped outdoor fan on a 45 °C afternoon	Often — clean the coil, clear the space
Low pressure or refrigerant	Suction pressure below the protected limit	A genuine leak, most often at a flare joint made on installation day	No
Sensor or thermistor circuit	A temperature probe reads open or short	A connector unseated by vibration, a rodent-damaged lead, or moisture in a monsoon-soaked outdoor unit	No, but it is a cheap part
Indoor–outdoor communication	The two boards have stopped talking	Loose or corroded interconnecting cable and terminal screws, far more often than a dead board	No — but insist the wiring is checked first
Inverter module or compressor drive	The power module has tripped or reports overcurrent	Supply abuse, heat, or a compressor drawing more than it should	No
Fan motor feedback	A fan is not turning at the speed commanded	An obstructed blower wheel, a seized bearing, or a failed motor	Sometimes — an obstruction is visible
Voltage out of range	Supply outside the machine’s working window	Weak evening supply or a generator; the territory of our guide to voltage stabilisers	Partly — the fix is upstream of the AC

What to check before you call

Three of the families above are provoked by conditions an owner can correct without tools, and together they account for a large share of first-heat-wave call-outs.

Filters and the outdoor coil. A choked filter or a coil packed with construction dust starves the machine of airflow and pushes it towards a protection trip. This is the first thing a good technician does anyway, and the rhythm that prevents it is in our guide to AC maintenance in India.
Space around the outdoor unit. A decorative grille, a shelf or a wall too close makes the condenser inhale its own exhaust, which is precisely the condition a high-pressure code reports.
The supply. Note the code against the time of day. A fault that only appears in the evening, when the colony load peaks, is pointing at voltage or at the circuit itself rather than at the machine — the ground covered by our guide to the wiring behind the AC.

Cutting power for a few minutes will clear most codes, and that is useful once: a fault that never returns was a transient. A fault reset every evening is not being fixed, it is being ignored, and in the drive and compressor families the repeated restarts are themselves damaging.

The code is not the diagnosis

This is where money is lost. A code names a symptom the machine can observe about itself, and several very different faults produce the same one. A communication error is reported identically whether the outdoor board is dead or a terminal screw has loosened over ten summers of vibration. A sensor code costs a few hundred rupees if it is the thermistor and several thousand if the technician decides the board must go with it.

So before a part is replaced, ask one question: what measurement confirmed it? For a board, that means the supply voltage at the terminals and the state of the interconnecting cable were checked first — the sequence set out in our guide to inverter PCB failure. For a refrigerant code, it means pressures were read and a leak was located, because topping up a circuit that leaks is exactly the practice our guide to AC gas refilling exists to warn about. A quotation offered without a measurement is a guess with a price tag.

Insist that the job sheet records the code, the measurements taken, the part number fitted and the warranty on that part. If the machine is still covered, that paperwork is what makes a claim work; what the cover actually includes is in our guide to AC warranty in India.

The codes that only appear in July

A distinct cluster of faults arrives with the rain rather than the heat. Water tracking into the outdoor enclosure, condensation on a board mounted in a driving-rain elevation, corroded terminals in coastal air, and lizards and rodents sheltering in a warm casing all produce sensor and communication codes that clear when things dry out and return with the next downpour. An intermittent fault that follows the weather is a sealing, drainage or earthing problem. Replacing the board without addressing the ingress simply buys the same failure again next season, which is why the enclosure and its mounting deserve as much attention as the part — the point behind our guide to where the indoor unit goes and its outdoor counterpart.

Frequently asked questions

What does an error code like E5 mean on my AC?

It depends entirely on the brand and the model year, and any site that answers that question without asking for your model number is guessing. On one manufacturer it may report a current or voltage protection, on another a sensor circuit. Check the sticker inside the front flap, the manual, or the brand’s support line with your model number in hand.

Can I reset an error code myself?

Yes — switching off at the isolator or the MCB for a few minutes clears most stored faults. Do it once. If the code returns, the protection is doing its job and the underlying condition is still there; repeatedly resetting a compressor or inverter fault risks turning a protected trip into a real failure.

Is a communication error always a bad PCB?

No, and this is one of the commonest over-diagnoses in the trade. The same code appears when the interconnecting cable is loose, corroded, damaged by rodents or landed on the wrong terminal. Ask for the terminals and cable to be checked and the supply voltage measured before any board is quoted.

Does an error code void the warranty?

A code is only a message from the machine; it voids nothing by itself. What can affect a claim is what caused it — unauthorised repairs, wiring outside specification or damage from a supply fault may fall outside cover. Keep the job sheet from every visit, including visits by whoever installed the unit.

Should the technician show me the code before starting work?

Yes, and it is a reasonable request. Ask to see the display or the blink pattern, and ask what it means on your specific model. A technician who can point to the service sticker and read the code from it is working from the manufacturer’s documentation; one who quotes a part immediately, without a measurement, is working from experience alone — which is worth something, but not the price of a board.