The inverter PCB: the other expensive failure in an Indian split AC

Updated September 7, 2026 · Claude AC · 2 sources cited

Contents (8)

Which board is being talked about
What board failure looks like
Why boards die here
The checks that must come before a PCB verdict
Repair the board, or replace it
Where the warranty stands
Preventing the next one
Frequently asked questions

Two verdicts end an Indian summer service call expensively: the compressor has gone, or the PCB has gone. The second is now far commoner than the first, because every inverter air conditioner sold in the last decade has replaced a simple contactor and capacitor with a power-electronics board that drives the compressor at a variable frequency. That board is clever, it is what makes the machine efficient, and it is also the component most exposed to everything an Indian supply throws at it.

Which board is being talked about

A modern split has at least two. Knowing which one is being condemned changes the price by several thousand rupees.

Board	Where it sits	What it does	Exposure
Indoor control board	Behind the right-hand side of the indoor unit	Reads the remote, runs the blower and swing motor, reads the coil and room thermistors	Low voltage, condensation, lizards
Outdoor inverter board	In the outdoor unit, on a heatsink	Rectifies the mains and drives the compressor at variable frequency via the power module	Mains surges, heat, rain, dust, rodents
Display or receiver board	Indoor front panel	Indicator LEDs and the infrared receiver	Cheap, occasionally the actual fault

The outdoor board carries the power module, and it is that module — not the microcontroller — which fails most often. A fixed-speed window or split AC has no inverter board at all: it has a control board and a run capacitor, which is why the same symptoms on a non-inverter machine usually cost a tenth as much to fix. The difference between the two architectures is explained in our guide to how inverter ACs work.

What board failure looks like

The indoor unit runs, the outdoor unit never starts. No hum, no fan, nothing. On an inverter machine this is a leading board symptom — but it is also what a broken communication wire, a blown outdoor fuse or a tripped internal protection looks like.
An error code on the display or a counted LED blink. Every manufacturer publishes its codes, generally in the user manual or on a sticker under the outdoor cover. Codes in the IPM, DC-link, over-current and communication families point at the outdoor board; sensor codes usually mean a ₹300 thermistor, not a board.
The unit starts, runs for a minute or two, then stops with a fault. Classic power-module behaviour under load: it passes the no-load test and fails when current rises.
Random restarts, or the machine ignores the remote while still cooling. Indoor control or receiver board.
A burnt smell, a visible black patch, or bulged capacitor tops on the board. Unambiguous, and worth photographing before anything is taken away.
The MCB trips the instant the outdoor unit engages. Could be the board, could be the compressor, could be the circuit itself — see our guide to the wiring, MCB and earthing behind an AC.

Why boards die here

Supply voltage. Not just surges after a power cut, but sustained low voltage and daily fluctuation. Power electronics tolerate a defined window; outside it, the DC-link capacitors and the module age quickly. This is the single largest cause in most Indian towns.
Lightning and switching surges. A nearby strike does not need to hit the building to induce a spike on the line, and monsoon storms coincide exactly with peak AC usage.
Heat. The board sits in an outdoor enclosure that is already at 45 °C, cooled by a heatsink that depends on airflow. A choked condenser and a cramped installation both raise board temperature, which is one more reason the placement rules in our guide to where the outdoor unit goes are not cosmetic.
Moisture and corrosion. Missing cover screws, an unsealed cable entry or a wall opening that funnels rain lets water reach the tracks. On the coast the same effect happens slowly with salt.
Lizards, rats and insects. A lizard crossing two terminals is a genuine, documented and remarkably common cause of a shorted board in Indian outdoor units.
Poor earthing. An AC without a real earth loses its reference and its surge path, and the board pays for it. The wiring guide above covers what a correct earth looks like.

The checks that must come before a PCB verdict

A board is the easiest component to blame because it cannot be tested by ear. Ask for evidence, in this order.

The error code, read aloud and identified against the manufacturer’s table. A technician who does not read the code is guessing.
Supply voltage measured at the outdoor terminals while the machine tries to start, not at a wall socket at 11 a.m. Voltage collapsing on load is a supply fault, not a board fault.
The fuse on the outdoor board and the connections. A blown 20 A fuse or a loose, blackened terminal is a cheap repair regularly billed as a board.
The communication wire between the units, including anywhere a rodent could reach it.
On a fixed-speed machine, the capacitor. Measured with a meter, not swapped by feel — the symptoms are covered in our guide to a split AC that has stopped cooling.
The compressor windings and insulation resistance before fitting a new board. Installing a board into a shorted compressor destroys it in seconds, and that is exactly how a repair doubles in price.

Repair the board, or replace it

Two routes exist. Component-level repair replaces the failed power module, capacitors or diodes on the existing board, and is a genuine trade practised well by specialist workshops in every major city. Replacement fits a new original board from the manufacturer.

Route	Indicative range	Typical warranty on the work	Sensible when
Indoor control board repair	₹1,500–₹3,000	1–3 months	Fault confined to the indoor unit
Outdoor inverter board repair	₹2,500–₹6,000	1–6 months	Out-of-warranty machine, good workshop, no water damage
New original board, mainstream brand	₹5,000–₹9,000 fitted	6–12 months	Machine under about seven years old
New original board, premium brand	₹8,000–₹14,000 fitted	6–12 months	Premium inverter platform worth keeping

These are indicative city ranges, not quotations, and they vary widely by brand, model year and spare availability. The decision rule is simple enough: on a machine under seven years old with a healthy compressor, an original board is usually worth it. Beyond ten years, with a board price approaching a third of a new 3-star inverter split, the money is better spent on the replacement — the same reasoning applied to a dead pump in our guide to compressor failure. And insist that the old board be returned to you; a repaired board resold as new is a known trick, and having the original in hand ends the argument.

Where the warranty stands

The headline “10-year compressor warranty” on Indian ACs almost never extends to the PCB. Standard cover is one year comprehensive on the whole product, sometimes extended to five years on the inverter board by particular brands as a selling point. Read the card rather than the advertisement, and note that the two exclusions applied most often to board claims are the absence of a stabiliser where the manual requires one, and repair by an unauthorised technician. Both are avoidable; both are the subject of our guide to what an AC warranty in India really means.

Preventing the next one

Give the machine a stable supply. A stabiliser with a wide window and surge protection, or a genuinely stabiliser-free inverter model whose specified voltage range covers what your street actually delivers.
Earth it properly and give it a dedicated circuit of the right rating.
Switch the AC off at the isolator during a storm if outages are frequent — the surge on restoration causes more damage than the cut.
Close the outdoor unit properly. Every screw in the cover, the cable entry sealed, the wall opening sloped outward.
Keep the condenser clean. Cooler power electronics last longer, which is one of the quieter returns on the servicing rhythm in our guide to AC maintenance in India.

Frequently asked questions

Can a PCB be repaired, or must it be replaced?

Most can be repaired at component level, and a good workshop will do it for roughly half the cost of a new board. The honest caveats are that a board soaked by rain or corroded by salt air is a poor candidate, that repair warranties are short, and that the same failure can return if the underlying cause — the supply, the earthing, the heat — was never addressed.

How do I know it is really the PCB and not the compressor?

They produce overlapping symptoms from outside the unit, so the distinction is made with instruments: the error code, voltage under load, the compressor winding resistances and insulation to earth, and the fuse. If a technician offers a board diagnosis without touching a multimeter, get a second opinion before authorising a spare.

Will a stabiliser actually protect the board?

It protects against the slow killers — sustained low voltage and daily fluctuation — which cause more board deaths than lightning does. It is not a lightning arrester, and a direct strike will pass through most domestic units. The realistic expectation is a materially longer board life in an area with weak supply, which is exactly what our guide to stabilisers for ACs sets out.

Is it worth putting a new board in a ten-year-old AC?

Only if everything else is sound and the price is well below a third of a new machine. At that age the compressor, the fan motor and the coils are all on borrowed time, and a new 5-star inverter split will cut the running cost enough to matter over the remaining years — the arithmetic is in our guide to what an AC adds to an Indian electricity bill.

Why do boards fail more in the monsoon?

Three causes arrive together: humidity and driven rain reaching the outdoor electronics, frequent power cuts with surges on restoration, and lightning activity. It is also the season when lizards and insects most often find their way into a warm enclosure, and when a badly sealed cable entry finally shows what it has been letting in all year.