Daikin Aircon Owner's Guide: Codes, Parts and Repair

Use these first if your Daikin unit is already showing a blinking light, error code, or repeat fault.

Daikin's current wall-mounted families are iSmile, iSmileEco+, iSmileEco, EZi and iSmart ENVi. The indoor sticker carries the family code: iSmile uses CTKS and CTKB, iSmileEco+ uses CTKM ZVMG, and iSmileEco uses CTKM and CTKP VVMG. EZi uses CTKC WVMG, while iSmart ENVi uses FTKM XVMG for single-split rooms. The register lists the outdoor unit that pairs with each family, and that code decides the capacity class for the whole home.

The register snapshot from 22 July 2026 lists multi-split outdoor units from the MKM50ZVMG at 4.15 kW to the MKM100ZVMG at 8.62 kW, all rated five ticks. Single-split registrations include the RKM25ZVMG at 2.45 kW and the RKM60ZVMG at 6.03 kW, rated five and four ticks. Older MKS outdoor units belong to earlier installations and do not appear in this snapshot.

Daikin cover depends on how the system entered the home, not only on the purchase date. Three conditions carry weight: an authorised installer commissioned the system, the e-warranty registration was completed, and the servicing file can be produced for the covered period. Product cover comes from the manufacturer, while the installation carries its own workmanship terms.

Registration ties the cover to the purchase record. Servicing receipts answer the question a claim asks about who worked on the unit and when. A regular schedule keeps those receipts easy to produce: filters every 2–4 weeks, general servicing every 3–4 months, and chemical servicing every 12–18 months. The daikin aircon warranty guide sets out how the terms run, so check the paperwork that came with the system before approving any repair.

Keep the model codes on the receipts as well as the dates. A claim moves faster when the registered model, the installed pair and the servicing record all name the same equipment.

Cover questions are worth settling before a technician opens the unit. Once a repair is authorised and parts are ordered, the paperwork position is harder to change.

Multi-split homes should keep the indoor code for every room as well. A claim or a diagnosis that names only the outdoor unit can leave the reporting room unclear.

Daikin shows alphanumeric codes on the indoor unit, and each one points at a circuit rather than a part. U0 means the system is short of refrigerant, which needs a leak test before any gas top-up. U4 means the indoor and outdoor units have lost transmission, usually along a wiring path or a board connection. A5 points at high-pressure control or freeze-up protection, often after a blocked coil or a fan moving too little air.

A6 covers the fan motor, A3 covers the drain level system, and H6 covers a position detection sensor. The Daikin error-code lookup resolves these rows and the wider residential table, including code combinations the display reports together. Write the code down exactly as shown and note when it appears, because an intermittent code narrows the fault differently from a constant one.

Codes describe what the board sees, not always what failed. A U0 reading can follow a slow leak at a flare joint, and an A5 reading can follow a coil that no longer sheds heat. A pressure test and a coil inspection separate the two before any part is replaced.

Parts depth and technician familiarity both favour Daikin, so the repair decision turns on the fault and the unit's age. Under five years, most faults trace back to the installation or to a small part. From five to eight years, board and capacitor faults are common, and a compressor failure is the point where a replacement comparison starts. Past twelve years, a major failure shifts the frame toward replacement, while minor fixes can buy time.