AC Error Codes Guide (LG, Samsung, Daikin, Carrier)

You come home to a hot flat, the AC light is blinking and the display shows something like E1, CH05 or A3. Which part is faulty, and can you fix it? This guide explains how error codes work, what the manufacturers say about codes on LG, Samsung, Daikin and Carrier units, which steps are safe to try, and when to call us. It's based on the manufacturers' own published support information, and where a brand doesn't publish a code list, we say so instead of guessing.

What an AC Error Code Actually Is

Modern air conditioners monitor themselves. Sensors read temperatures, fan speed, current, pressure and communication between the indoor and outdoor units. When a reading is missing or outside its normal range, the control board stops the unit and shows a code, either on the display or as a pattern of blinking lights. The code tells a technician where to start looking. It doesn't always name the failed part, since a sensor code can be caused by the sensor, its wiring, the circuit board or a power disturbance.

Why You Can't Use One Code List for Every Brand

The same code can mean different things on different brands, and even on different series from the same brand. An "E1" on one unit may be a sensor fault, and on another a circuit board or communication fault. For that reason, a generic table from a random website can mislead you. Use the code list for your exact model, found in the manual or on the manufacturer's support page, and treat the examples below as a guide to how each brand reports faults.

First Steps for Any Error Code

The reset time varies. LG's UAE support article suggests unplugging the unit or switching off its breaker for about five minutes, while Carrier's mini split guidance suggests waiting about 20 minutes before restoring power. Follow the instructions for your own brand.

LG Air Conditioner Error Codes

LG groups its codes by the type of fault. According to LG's UAE Help Library article on air conditioner error codes, sensor-related codes include CH01, CH02, CH06, CH12, CH41 to CH48, E1, E2, E3, E7, E8, F2 and F3, and these point to a faulty or loose temperature or pipe sensor, a main board error or a temporary electrical problem. Codes CH21, CH23, CH26, CH29 and E9 relate to the outdoor unit's compressor or its control circuits, and the possible causes include a temporary power issue, a compressor fault or a faulty electrical component.

LG's advice is to reset the unit, then request a technician visit if the code remains. If the same code returns after a reset, LG says to stop using the unit and request service, and warns against opening the unit or replacing internal parts yourself. If the code disappears and the unit runs normally, you can usually carry on using it, but a repeat error may mean a wiring or circuit problem. For repairs on LG and other split units, see our split AC repair page.

Samsung Air Conditioner Error Codes

Samsung's UAE support page separates codes into two groups. The first group isn't a fault at all, and these are the codes you may see during normal operation.

• CF: filter cleaning reminder. Clean or replace the indoor filters, then clear the reminder with the remote
• CI: the auto clean function is running after the unit is switched off, and no fix is needed
• dF: auto defrost is running in heating mode. Samsung says this is a protective mode for the outdoor unit, not a defect

The second group needs a service centre or qualified technician. Samsung's page lists these examples, shown as a "C1" or "E" prefix followed by a number that blinks on the display.

• 21 (C1 or E21): room temperature sensor is defective
• 22 (C1 or E22): heat exchanger temperature sensor is defective
• 54 (C1 or E54): the fan isn't rotating
• 63 (C1 or E63): data on the main control board is incorrect or missing

Samsung notes that not every alarm is a product defect, so check the user-level codes first, and write down a blinking code to give to the service centre. For a unit that shows a fault code and won't run, our AC repair team can diagnose it.

Daikin Air Conditioner Error Codes

Daikin publishes a self-diagnosis reference by malfunction code. The codes below are taken from Daikin Global's "Simple Self-Diagnosis by Malfunction Code" document, which covers several product types including room air conditioners, SkyAir and VRV. Which codes apply depends on the product, so check your own manual.

• A1: indoor unit circuit board malfunction
• A3: drain level control abnormality, such as a clogged drain, drain pump or float switch fault
• A5: high-pressure control in heating or freeze-up protection in cooling, linked to a clogged filter or a thermistor fault
• A6: indoor fan motor malfunction
• C4 and C9: indoor heat exchanger or suction air thermistor malfunction
• E1: outdoor unit circuit board fault
• E3: high-pressure switch actuation, for example from a dirty outdoor heat exchanger
• E4: low-pressure switch actuation, or an abnormal drop in low pressure
• E5: inverter compressor motor lock or overheat
• F3: discharge pipe temperature malfunction
• U0: shortage of refrigerant
• U2: power supply malfunction or momentary power failure
• U4: transmission fault between the indoor and outdoor units

Daikin's troubleshooting page also says a flashing operation light likely means the unit is malfunctioning, and advises resetting the breaker and contacting Daikin if the problem persists. Several of these codes, such as A3 or A5, may be related to drains or filters you can check, and our guide to why an air conditioner leaks explains the drain side.

Carrier Air Conditioner Error Codes

We couldn't find an official Carrier error code list that applies across its models, and Carrier's own mini split repair guide doesn't list codes. Carrier systems vary a great deal between series, and the codes depend on the specific model, so any list online that claims to cover all Carrier units should be treated with caution.

What Carrier does advise is to record any codes shown on the indoor unit or remote so a technician can use them in diagnosis. It suggests a power reset, with the system off and disconnected for about 20 minutes, and says to call a professional if the problem returns, if you suspect a refrigerant leak, or if the outdoor unit isn't running while the system is calling for cooling. Check your unit's manual for the code list, or send us the model number and code. For larger systems, our central AC repair page explains how we approach them.

What the Common Types of Code Usually Point To

Codes You Can Deal With Yourself

A few codes are really reminders or protection modes, and some faults are caused by simple things you can check. Filter reminders such as Samsung's CF can be cleared by cleaning the filter. Defrost and auto clean modes pass by themselves. A dirty filter or a blocked outdoor unit can contribute to freeze-up or high-pressure protection, so clean the filter and clear the outdoor unit. The US Department of Energy advises cleaning or replacing filters about every month or two in the cooling season, and more often in dusty conditions, and our guide on how dirty AC filters affect airflow explains why this matters in Abu Dhabi.

Codes You Should Never Try to Fix Yourself

• Compressor, inverter and drive circuit codes
• Circuit board, EEPROM and communication faults
• Refrigerant shortage or pressure switch codes
• Any code that comes back after a power reset
• Any code with a burning smell, sparks, tripping breakers or smoke

These involve live electrical parts and the sealed refrigerant system. LG's own article warns against disassembling the unit or replacing internal parts yourself, because of the risk of fire, electric shock or injury. If the cause may be a refrigerant leak, our AC gas refill page explains how we find the leak before recharging.

What to Tell the Technician

A good description saves time and often saves a second visit. Tell us the brand and model number, the exact code and whether it blinks or stays on, when the fault began, and what the unit was doing. Mention any recent power cuts, storms or work on the building, and say whether the code appears after a reset. Photos of the display and the model label are very helpful.

Why Error Codes Appear More Often in Hot, Dusty Conditions

Abu Dhabi's heat, dust and long running hours put extra stress on AC units. Dust blocks filters and coils, which can trigger freeze-up or high-pressure protection. Heat pushes components closer to their limits, and power fluctuations can trigger supply and communication codes. Regular servicing is the best way to keep codes away, and our AC maintenance service covers the cleaning and checks that prevent many of them.

If your AC is showing an error code you can't clear, message or call ALHUD Technical LLC with the brand, model and code. We'll tell you what it usually points to, diagnose it on site and give a fixed quote before any work begins.

Frequently Asked Questions