Daikin AC Outdoor Unit Error Codes (E, F & H Families): Meaning & Fixes

Daikin's E, F and H codes belong to the outdoor unit — the half of the system that lives in the weather with the compressor, the pressure switches and the refrigerant circuit's heavy machinery. E reports events (a switch tripped, a compressor locked, a fan failed), F reports the refrigerant circuit's temperatures and charge, and H reports the watchdogs themselves: switches, signals and sensors. Almost everything on this page is licensed-technician territory once a basic airflow check has failed, because almost everything here touches refrigerant or mains-voltage components. This guide explains each family, the few owner checks that are real, and why these codes should be quoted, not repeatedly reset.

E3 — high pressure switch activated: the classic outdoor code

E3 means refrigerant pressure on the high side climbed until the high-pressure switch cut the system out to protect the compressor. It is a protection success, not a component failure, and Daikin's VRV chart reads like a checklist of everything that makes pressure climb: the outdoor heat exchanger is dirty, airflow over the outdoor coil is restricted, a stop valve is closed, the refrigerant piping is clogged, or the system is overcharged. The owner version of that list is short and worth doing properly: switch off, clear leaves, bags, garden debris and anything stored against the outdoor unit, check that its inlet and outlet both breathe freely (a unit boxed in by a fence panel or a new deck overheats in its own exhaust), and if the coil face is visibly matted with dirt, that is a service clean, not a garden-hose blast into the electrics. Retry once after clearing airflow. An E3 that returns with a clean, clear coil has left owner territory: charge weighing, stop-valve and piping checks and the switch test are gauge work. Note the pattern for the technician — E3 only on the hottest afternoons points at airflow and charge margins; E3 within minutes of start-up, every time, points at a closed valve or a serious restriction.

E4 — low pressure malfunction: the starved circuit

E4 is E3's mirror: pressure on the low side fell abnormally and the low-pressure protection stopped the system. Where E3 is a circuit that cannot breathe out, E4 is a circuit that is not being fed. Daikin's chart gives the branches plainly — refrigerant shortage, a closed stop valve, a clogged refrigerant path, or the sensing side lying (a defective low-pressure sensor or an outdoor PCB misreading it). Refrigerant shortage leads the list in real life, and shortage always means a leak: systems do not consume refrigerant, so an E4 system has lost charge somewhere — a flare joint, a coil, a valve stem — and the repair sequence is find the leak, repair it, evacuate, recharge by weight. Topping up an E4 system without the leak search is paying for the same code twice, and on many models repeated low-pressure running also starves the compressor of the cool suction gas it depends on, which is how E4 grows into F3 and then a compressor. There are no owner checks for E4 beyond confirming the outdoor unit is actually powered and unobstructed; everything diagnostic is gauges and leak detection. Stop the system and call — and tell the technician if the cooling had been fading for weeks first, because that slow fade is the leak's signature.

E5 and E6 — compressor lock, overload and failed start-up

E5 and E6 are the compressor codes, split by platform. On inverter systems E5 is compressor lock detection — the drive tried to run the compressor and it would not turn, or its motor overheated under the attempt; residential charts word the same event as the overload (OL) starting. On standard (non-inverter) and SkyAir models, E6 covers the fixed-speed compressor: lock, overcurrent, or a start-up that fails outright. Daikin's cause lists converge — a compressor mechanically seized or electrically failed, a stop valve left closed so the compressor starts against a wall of pressure, an expansion valve that will not open, refrigerant shortage cooking the motor, or the control/inverter board feeding it badly. None of these branches has an owner step beyond stopping. Repeatedly power-cycling a locked compressor is the single most expensive habit in this whole code table: each attempt slams the drive and the windings, and an inverter board that was healthy on the first E5 can be a casualty by the fifth reset. One reset to confirm the code is honest; after that, the unit stays off until a technician has separated compressor from valve from board with instruments. If the unit is older, get the compressor verdict before authorising board parts — the diagnosis order matters to the bill.

E7 and H7 — the outdoor fan and its signal

The outdoor fan has two codes because it can fail two ways. E7 is the fan motor system malfunction: the motor is locked, overloaded, over-current, or not turning at all — a failed DC motor, a fan physically blocked by debris or ice, or the harness between motor and PCB broken. H7 is subtler: the motor's position/rotation signal is abnormal, meaning the control cannot verify how the fan is turning even if it turns. The distinction matters because the fan is the outdoor coil's lungs; a fan running slow or unreported drives high pressure (E3), heats the inverter (L4) and cooks the compressor's discharge (F3), so fan codes often arrive holding hands with pressure codes — fix the fan story first and the pressure codes frequently retire with it. Owner checks are visual and power-off only: debris in the fan guard, a branch through the grille, ice in winter. Never reach through the guard of a unit that can start itself, and never spin the blade to 'help' it — a DC fan generates voltage when spun. Motor and signal diagnosis happen inside a mains-voltage compartment, so both codes are technician work once the fan is visibly free.

E9 and EA — the valves: expansion and four-way

Two E codes cover the refrigerant circuit's valves. E9 is the outdoor electronic expansion valve — the motorised metering valve (on VRV there are several, main and subcooling) whose coil or moving part has faulted, or whose connector has simply come off the board. Without it the outdoor unit cannot meter refrigerant for the whole system, so E9 is a full stop with a small part at the centre: coil, connector, or the PCB output driving it, in that order of probability and price. EA is the four-way valve, the reversing valve that decides whether the system heats or cools. Its chart branches are the valve or its coil, a thermistor lying about temperatures so the changeover logic misfires, refrigerant shortage upsetting the pressures the valve shifts on, or the outdoor PCB. The owner's symptom picture for EA is theatrical — a unit blowing warm in cooling mode or cold in heating, or one that never changes over after winter — but the repair is not: valve coils are replaceable, valve bodies mean refrigerant recovery and brazing. Both codes are technician territory; your contribution is an accurate story of which mode failed and whether the problem followed a service visit, because a disturbed E9 connector is a classic post-service fault.

F3 — discharge temperature malfunction: the compressor is cooking

F3 is the outdoor temperature code that deserves the most respect. The compressor's discharge pipe is the hottest point in the system, and F3 means its temperature ran abnormally high until the protection control stopped the unit. A compressor discharges hot gas in proportion to how hard it works and how little cool suction gas returns to cool it — which is why Daikin's chart for F3 points straight at refrigerant shortage, a closed stop valve and a clogged circuit: a starved compressor is an overheating compressor. F3 rarely arrives first. Its usual biography is weeks of fading performance (the leak), perhaps an E4 or U0 that was reset and run through, and then F3 announcing that the compressor has been cooking long enough for its protection to insist. Read it as a late-stage code: the question is no longer only 'why is it hot' but 'how much damage did the heat do' — oil degrades, windings suffer, and a compressor run repeatedly into F3 is being spent. There are no owner checks for F3. Stop the unit, leave it stopped, and when you call, report the whole code history if you know it; a technician who hears 'F3 after a month of weak cooling' starts at the leak and the compressor's health, in that order.

F6 — overcharge detection and high-pressure control

F6 is the charge code, and its meaning shifts slightly by platform in a way Daikin's own documents state openly. On VRV the chart calls it refrigerant overcharge detection: the system has measured more refrigerant behaviour than its weighed charge explains, almost always because someone added refrigerant the system did not need — classically after misreading another fault as 'low gas'. On residential splits the operation manual words F6 as high-pressure control in cooling: the control is actively limiting operation because high-side pressure is too high, which an overcharge causes, but so do a filthy outdoor coil and strangled airflow on a hot day. The diagnostic order follows: airflow and coil cleanliness first (owner-visible, free to check), charge second (scales and gauges, licensed). The lesson F6 teaches is about refrigerant itself: charge is a weight printed on the unit's rating plate, not a pressure you top up to by feel, and 'a bit extra for luck' is a fault with a code of its own. If F6 appeared shortly after a service where refrigerant was added, say so when you call — it rearranges the diagnosis completely, and correcting an overcharge means recovering the excess into a cylinder, never venting it.

H3 and H4 — when the switch itself is the fault (and H9/H6/H8)

The H family's neatest idea is its separation of actor from instrument. E3 means the high-pressure switch did its job; H3 means the high-pressure switch itself has malfunctioned — a failed switch or its connector contact, reporting pressure that is not there or failing to report pressure that is. H4 is the same idea on the low side, the counterpart to E4. This is why a technician confronted with H3 does not simply swap the switch: the diagnosis must prove the real pressure is healthy before the messenger is blamed, which is gauge work by definition. The rest of the outdoor H shelf is signals and sensors. H9 is the outdoor air thermistor, the sensor that tells the system the weather it is working in; defrost and capacity decisions lean on it. On residential inverter splits, H6 is the compressor position-detection halt — the drive has lost the rotor-position signal it steers by — and H8 is the current transformer (CT) abnormality, the sensor that watches compressor current; both stop the unit because the drive is flying blind without them, and both are board-and-compressor diagnosis. All of the H shelf is technician work, and all of it is cheaper diagnosed with the exact code recorded than with 'some H code' remembered.

E1 and E2 — the outdoor board and the leakage detector

E1 is the outdoor unit's main PCB declaring itself defective — the outdoor counterpart of A1. Surges are its classic author, with heat and moisture as slow accomplices in a box that lives outside. One full power reset at the isolator is the owner's whole playbook; a returning E1 is board diagnosis and replacement, and on VRV the replacement board then needs the system's configuration restored, which is why E1 on a multi system is installer work, not a parts swap. E2, found on VRV, is different in kind: the current leakage detector was activated, meaning current is escaping to earth somewhere in the outdoor unit — moisture in a terminal box, insulation failing on a compressor or fan motor, a chafed cable. E2 is a safety device reporting a shock hazard, and it outranks every convenience argument: do not reset it repeatedly, do not run the unit 'to see', and treat a breaker that trips alongside it as the same message in a louder voice. A licensed technician finds leakage with insulation testing, component by component. Of all the codes on this page, E2 is the one where the correct owner action is simply: off, and call.

Shared outdoor causes — and the professional line

Stand back from the outdoor families and three roots explain most of the table. Airflow and heat: a coil matted with dust, a fan failing, a unit suffocating in a boxed corner — these manufacture E3, F6, L-family heat and eventually F3, in that rough order, which is why the annual service that actually washes the outdoor coil is fault prevention, not cosmetics. Refrigerant quantity: too little starves (E4, U0, F3), too much chokes (F6, E3), and both errors are corrected the same way — recover, repair, evacuate, weigh — never by topping or bleeding to a guessed pressure. Electricity: surges and tired boards write E1, E5/E8 drive codes and half the H shelf. The professional line on this page is the strictest on the site. Owners: clear the air path, look (power off) for a jammed fan, note the code exactly, reset once. Everything involving refrigerant piping, stop valves, pressures, compressors, inverter boards, motors inside the guard, or any E2 event is licensed work — legally restricted in many countries, and dangerous in all of them: refrigerant under pressure, stored charge in inverter capacitors, and a compressor that can be killed by the restart habits that feel like troubleshooting. Quote the code, the mode it failed in, and the weather that day; outdoor codes are diagnosed half by instruments and half by that story.

Key takeaways

• E3 on the hottest afternoon with a dirty coil is airflow until proven otherwise; E3 within minutes on a mild morning is a valve or restriction — tell the technician which kind you have.
• Never top up refrigerant for E4/U0 without a leak search: the system does not consume refrigerant, so shortage always means a leak with an address.
• One reset to confirm a compressor code (E5/E6), then off. Repeated restarts are how a compressor fault collects an inverter board as well.
• E2 is not a reset-and-see code: leakage protection means current is going somewhere it should not, and the unit stays off until it is found.

Resetting the Daikin air conditioner

Daikin codes are condition reports, not latches to be cleared by ritual: the code clears when its condition clears. Daikin's VRV IV reference guide puts the owner-level reset plainly — depending on the level of the malfunction code, you can reset the code by pushing the ON/OFF button; if it will not reset, ask your installer. The fuller reset is a power reset at the isolator/breaker: switch the system off for several minutes (both indoor and outdoor units — on a split they are usually on one isolator), then back on and let it run; Daikin's manuals note the system does not restart instantly (a safety device holds the compressor off for about 3 minutes, and a VRV system can take up to about 12 minutes after power-on to finish its communication/addressing checks). Fault history is separate from the live code: on wired remote controllers the stored malfunction history shown in inspection (check) mode is cleared deliberately — hold the ON/OFF button for 5 seconds or more while in inspection mode, and the code flashes twice, changes to '00' (normal) and the unit number to '0' before the display returns to normal mode. Never clear history before you have written the code down, and never treat a reset as a repair: a code that returns after a clean power reset is a confirmed, present fault.

Frequently asked questions

Related guides

Facts on this page were checked against manufacturer documentation: www.daikin.com.mt · daikinac.com · www.daikin.ch · www.manualshelf.com · www.manualshelf.com · www.manualshelf.com · mcgrp.ru · mcgrp.ru · dwt-front-dev.daikincomfort.com