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GUIDE 9 min read · Updated

VRF and VRV Troubleshooting: Fault Codes for Every Major Brand

How VRF fault codes read, the same fault on thirteen brands side by side, and what the manuals say about resets. Every code links to its entry in the brand guide.

By AirNexus · HVAC controls

VRF and VRV: The Same Technology

VRF (variable refrigerant flow) is the industry term. VRV (variable refrigerant volume) is Daikin’s name for its own systems. Both describe the same idea: one outdoor unit, or a bank of them, serves many indoor units on one refrigerant circuit, and the system varies the refrigerant flow to each indoor unit to match its load.

How VRF Fault Codes Read

Every manufacturer has its own code list, and the same code means different things on different brands. E1 is high-pressure protection on Gree GMV, a communication error between the indoor unit and remote control on MHI KX, an outdoor PCB abnormality on Daikin VRV and a phase sequence error on Midea V5. Always look the code up against the brand and series on the unit label.

Codes show on the wired controller, the outdoor unit’s display or LEDs, the indoor unit’s LEDs and any central controller. Several brands give the detail in a second place: Gree shows a group code (P0, P1) on the wired controller and the exact code on the outdoor board; Fujitsu’s remote shows 86 where the outdoor display shows 86.4; MHI’s outdoor display adds a sub-code (E36-1); LG’s outdoor display shows CH21 as 211 on the master frame.

Brand guideSystem coveredWhat a code looks like
CarrierXCT and X-Power VRFE0, P1, H4
DaikinVRV III and VRV IVU4, E3, L5
FujitsuAirstage V-II12, 86.4, A4
GreeGMV6C0, E4, P8
HitachiSET FREE FSXN03, 31, 53
LGMulti VCH05, CH21, 211
MideaV8, Atom T and V5C21, P3, E1
Mitsubishi ElectricCity Multi6607, 1302, 5102
Mitsubishi Heavy IndustriesKXE5, E36-1, E40
PanasonicECOi 2-way and Mini ECOiE04, P29, H06
SamsungDVM SE101, E464
ToshibaSMMS-eE04, P26
TraneVRF (United States)6607, 4250
Stiebel EltronHeat pumps (WPM)10004, 50004

Split systems and ducted units use their own lists: Daikin split system and ducted and Fujitsu split system and ducted.

For licensed technicians. This guide is general information to help you find the right part of the manufacturer’s service manual. Isolate power before opening any unit, follow the manufacturer’s procedures, and leave refrigerant work to a licensed refrigerant technician (in Australia, an ARC licence holder).

The Same Fault on Every Brand

The six fault families you will meet on any VRF system, with the code each brand uses. Every code links to its entry in the brand guide, taken from that manufacturer’s own manual.

01
Communication between indoor and outdoor units
What the manuals point to
The manuals point first to the communication wiring and its terminations, power to every unit on the line, and the address settings, then to the PCBs at either end.
The code on each brand
In the AirNexus app. On a Nexus 8, 16 or 32 this code arrives as a push notification with the unit address and the time it happened, and Nexus iQ Diagnostics shows the raw data straight off the bus.
The same fault, on your phone

Know about U4 before the tenant does.

A Nexus controller sits on the system's control network and logs every fault the moment it happens: the code, the unit address, and the time. It lands in the AirNexus app before anyone calls you.

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02
High pressure
What the manuals point to
A protection stop on the refrigerant circuit. The manuals list airflow at the condenser (coil, fans, filters), a closed valve, too much refrigerant and the pressure sensor or switch itself.
The code on each brand
In Nexus iQ. The outdoor unit’s pressures and temperatures are read live where the system reports them. Chart them in Trends, from the past 6 hours to 30 days, to see what led up to this code.
03
Low pressure or refrigerant shortage
What the manuals point to
The manuals point to closed service valves, insufficient refrigerant, a blocked expansion valve or strainer, and the low pressure sensor.
The code on each brand
In Nexus iQ. The outdoor unit’s pressures and temperatures are read live where the system reports them. Chart them in Trends, from the past 6 hours to 30 days, to see what led up to this code.
04
Discharge temperature too high
What the manuals point to
The compressor is running too hot. The manuals list insufficient refrigerant, the expansion valve, airflow and the discharge temperature sensor.
The code on each brand
In Nexus iQ. The outdoor unit’s pressures and temperatures are read live where the system reports them. Chart them in Trends, from the past 6 hours to 30 days, to see what led up to this code.
05
Compressor drive and overcurrent
What the manuals point to
Inverter and compressor faults. The manuals start with the power supply and phases, the compressor windings and insulation, the wiring to the compressor and the inverter board. Discharge the DC bus before touching the boards.
The code on each brand
In Nexus iQ. Compressor frequency, current and fan speed are read live where the system reports them, and Health scores each unit over 24 hours, 7 days or 30 days.
06
Drain and float switch
What the manuals point to
Indoor unit drain faults. The manuals list the float switch, the drain pump and the drain pipe.
The code on each brand
In Nexus iQ. The fault shows in Findings as a plain-English sentence, with how long it has been active.

Reset or Investigate: What the Manuals Say

A reset clears the display, not the cause: a code that comes back after a reset is telling you the condition is still there. The manuals add brand rules worth knowing before you power anything down.

Refrigerant work is for a licensed refrigerant technician (in Australia, an ARC licence holder), and electrical work on the outdoor unit is for a licensed electrician.

What Nexus iQ Shows Alongside the Code

A fault code tells you what tripped. On a Nexus 8, 16 or 32, Nexus iQ reads the VRF system’s own data off its control line, so you can see the readings around a code before anyone goes to site. What you see depends on what the system reports.

When you seeThe code tells youIn Nexus iQ
Communication codes (U4, 6607, CH05, C0)A unit has stopped talking to the systemPush notification with the unit address and time. Diagnostics marks a reading that has stopped updating as stale, with its age.
Pressure codes (E3, 1302, P1, E1)A pressure protection has trippedHigh and low pressure live in Diagnostics, charted in Trends from 6 hours to 30 days.
Discharge temperature (1102, CH32, E4)The compressor is running too hotDischarge temperature live, charted in Trends to see what led up to it.
Compressor drive (L5, 4250, P5)Inverter or compressor protectionCompressor frequency and power draw live, with a Health score per unit over 24 hours, 7 days or 30 days.

The same faults reach the free AirNexus app as push notifications. See Nexus iQ.

Run your VRF systems on AirNexus

AirNexus supplies the controls and your HVAC contractor installs them. One app covers every unit on the site.

VRF systemsNexus 8, 16 and 32Connects to the VRF central control line with one 2-core cable, so every indoor unit is controlled from one app and its faults reach your phone. No gateway per unit.See VRF control → Splits and ductedFCU GatewaySplit or ducted units on the same site? One FCU Gateway per unit connects each one to the same app, across 15 brands.See the FCU Gateway → Free appThe AirNexus appFault notifications, schedules and control for the whole site, on iPhone and Android.About the app → For contractorsSend us your jobTell us about the site and the system. We’ll come back with the AirNexus controls to suit.Send a job →

Not sure which fits? Find your system. AirNexus supplies Australia and New Zealand; distributors and project teams elsewhere can register as a partner.

Sources

Each brand guide lists the manufacturer manual its codes come from. The codes named on this page are taken from these guides.

VRF and VRV fault codes: frequently asked questions

What is the difference between VRF and VRV?

Nothing technical. VRF (variable refrigerant flow) is the industry term and VRV (variable refrigerant volume) is Daikin’s name for its own systems. Both run many indoor units from one outdoor unit or bank on one refrigerant circuit.

Are VRF fault codes the same across brands?

No. Each manufacturer has its own list and the same code can mean different things: E1 is high-pressure protection on Gree GMV, a communication error between the indoor unit and remote control on MHI KX, an outdoor PCB abnormality on Daikin VRV and a phase sequence error on Midea V5. Use the guide for the brand on the unit label.

Is it safe to reset a VRF fault code?

A reset clears the display, not the cause. Some codes cannot be cleared from the controller at all, such as Hitachi EE, and some brands set rules for powering down, such as Gree’s instruction to power every outdoor unit in a modular system off and on together. Refrigerant work is for a licensed refrigerant technician.

Can I see VRF fault codes remotely?

Yes. A Nexus 8, 16 or 32 on the VRF central control line sends each fault to the free AirNexus app as a push notification, with the unit address and the time it happened. Nexus iQ lists it in Findings & Insights, and the Diagnostics view shows the system’s live readings around it. See VRF control.

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Fault codes for other brands

Carrier XCT VRF fault codes

Daikin VRV fault codes

Daikin split system and ducted error codes

Fujitsu VRF fault codes

Fujitsu split system and ducted error codes

Gree VRF fault codes

Hitachi VRF fault codes

LG Multi V VRF fault codes

Midea VRF fault codes

Mitsubishi Heavy Industries VRF fault codes

Mitsubishi Electric City Multi VRF fault codes

Panasonic VRF fault codes

Samsung DVM VRF fault codes

Stiebel Eltron fault codes

Toshiba SMMS VRF fault codes

Trane VRF fault codes (United States)

All fault code guides

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