Why Is My AC Light Blinking? Reading the Error Code

First: count the blinks and write them down

Free, takes two minutes, and it is worth more than everything else on this page. Do it before you switch the unit off, because switching off can clear the code and you will lose the information.

• 1. Note which light is blinking. Most indoor units have several: Power or Run, Timer, Sleep or Economy, Defrost, and sometimes a filter or cleaning indicator. Different lights mean different things, so “the timer light” is a real clue. If your unit has a digital display instead, note the letters and digits exactly, for example H6 or E5.
• 2. Count the flashes in one burst. The pattern almost always goes: a group of flashes, a longer pause, then the same group again. Count one full group. Do it two or three times to be sure of the number.
• 3. Note whether two lights flash together or alternate. Some schemes use combinations, and that detail changes the meaning entirely.
• 4. Photograph or film it. Ten seconds of video on your phone captures the pattern perfectly and removes any argument about what you counted. Send it to the technician before the visit if you can.
• 5. Note what the AC is actually doing. Blinking and cooling normally, blinking and blowing warm air, blinking and refusing to start, or blinking after it shut itself down. That context narrows the code family a long way.
• 6. Then look for the manual. The code table is in it. If the paper manual is long gone, the model number is on a sticker on the side or under the front flap of the indoor unit, and the manufacturer publishes the manual for that model.

What is a blink pattern, and where do I find what it means?

A blink pattern is a fault code shown on a unit that has no screen to print words on. The board detected a specific condition, matched it to a numbered fault in its own list, and flashes that number at you.

Three things follow from that, and they are the reason this page exists:

• The code is brand-specific. Four blinks of the timer light means one thing on one brand and something completely different on another. Anyone who tells you what your code means without asking which brand and model you have is guessing. Do not act on a diagnosis given over the phone on the code alone.
• The code identifies a family, not a part. It will tell a technician that a sensor circuit is out of range, or that the indoor and outdoor units are not communicating. It will not tell them which wire, which connector or which board. That still needs a visit. But it turns an hour of hunting into a targeted check.
• The code is documented, and you are entitled to see it. The table is in the manual and often on a label inside the unit. If a technician quotes you for a part, it is entirely fair to ask them to show you the code in the table and explain how it points there.

Two lights are worth understanding separately. On many units the Timer light doubles as the general fault indicator, which is why so many people search for a blinking timer light when they have not set a timer at all. And on inverter units, a blinking Power or Run light during operation is often normal — it can simply mean the compressor is ramping up or the unit is in its restart delay. A slow, steady blink during normal cooling is usually status. A fast or grouped blink with the unit stopped is usually a fault.

The common families of AC error code

Whatever the brand, nearly all blink codes fall into one of a handful of groups. Knowing the family tells you how worried to be and who to call.

• Sensor faults. The commonest by a wide margin. An AC has several small thermistors — room temperature, indoor coil, outdoor coil, sometimes the discharge pipe. If one goes open or short circuit, or its connector works loose with vibration, the board cannot read it and flags a fault. The unit may still run oddly, or refuse to run. These are small, inexpensive parts and a common, honest repair.
• Communication faults between indoor and outdoor units. The two halves of a split AC talk to each other over a signal wire in the interconnecting cable. A corroded terminal, a rodent-chewed cable, water ingress at a badly sealed joint or a loose connection in the outdoor terminal block breaks that conversation and the board reports it. In Delhi this is often a wiring or weather-sealing problem rather than a failed board — insist the cable and terminals are checked before anyone condemns electronics.
• Voltage protection faults. The board watches the supply and refuses to run outside a safe window. On a Delhi summer afternoon, with the colony load at its peak, the voltage can sag far enough to trigger this. The unit stops, flashes, and works perfectly at midnight. This is the machine protecting itself, not breaking. See our voltage and stabiliser tips.
• Overload and protection faults. The compressor or the outdoor fan drew too much current, or ran too hot, and the board shut it down. A dust-choked outdoor coil in a boxed-in balcony is the usual reason here. Related to this is our page on an AC that turns off by itself.
• Fan or motor faults. The board expects a feedback signal telling it how fast a fan is turning. A seized bearing, a blocked fan or a failed motor stops that signal and raises a code.
• Filter or service reminders. Not faults at all. Covered in the next section.

What is not usually the answer, despite being the most quoted: a dead compressor, or a board that must be replaced outright. Both exist, but a code is a starting point for diagnosis, not a verdict. Our guide on inverter AC PCB repair covers what actually drives that job when a board genuinely is the problem.

When the blinking light is not a fault, and how to reset it

Before you call anyone, rule out the cases where nothing is wrong.

• A filter-clean reminder. Many units count running hours and then flash a filter or clean indicator to tell you it is time to wash the mesh. This is a calendar, not a diagnosis — the unit has no idea whether your filter is actually dirty. Wash the filters, dry them fully, refit them and clear the reminder using the reset or filter button described in the manual. Our AC filter cleaning tips cover the washing part.
• A timer that is actually set. If someone set a timer or sleep function, the timer light is on or blinking because it is doing its job. Cancel the timer and see if the light goes.
• Defrost or ramp-up status. A slowly blinking run light while the unit is starting, or during a defrost cycle on a hot-and-cold unit, is normal operating status.
• The restart delay. After a power cut, most units wait roughly three minutes before restarting the compressor, and some blink while they wait. Delhi’s summer cuts and restorations mean this happens often. Give it five minutes before deciding anything is wrong.

How to reset properly. Once you have recorded the pattern, switch the AC off at the remote, then off at the wall socket or the dedicated breaker, wait five full minutes, and switch it back on. That is the whole reset procedure on almost every unit — there is no secret key combination, and any sequence involving opening a panel is not a homeowner job. If the code clears and does not come back, it was a transient condition, very often a voltage dip. If it comes back within minutes or hours, it is a real fault and the reset has only bought you time.

When to call a technician, and what to say

Call once you have counted the pattern, checked the filters and tried one clean reset. Then lead with the code, because that is the whole point of this page.

• Say the brand and the model number. The code means nothing without them. The model number is on a sticker on the indoor unit.
• Say exactly which light and exactly how many flashes. “The timer light flashes five times, pauses about three seconds, then repeats”, or the display code as printed.
• Say what the unit does. Runs and cools, runs and blows warm, starts and stops after a few minutes, or will not start at all.
• Say when it started and whether it follows a pattern — only on hot afternoons, only after a power cut, only since the last service.
• Send the ten-second video if you can. It settles the question before anyone arrives.

Things to hold firm on. Ask the technician to show you the code in the manufacturer’s table and explain how it points at the part being proposed. Ask for the interconnecting cable and the terminal connections to be checked before any board is condemned, because loose and corroded terminals cause a lot of communication codes in Delhi. Ask what was measured — supply voltage and running current are real numbers. Ask for the old part back. And get a second opinion before agreeing to a control board or a compressor on the strength of a code alone.

If the code came with another symptom, the matching page will help: an AC that is not cooling, an AC blowing hot air, an AC that will not turn on, or an outdoor unit that is not running.