A facilities manager in a Moorgate office block rang us in a mild panic because every indoor unit on three floors was flashing an error code simultaneously. Fifty staff sitting in a building with no climate control, the MD asking questions, and all the FM company could tell him was “it’s showing a fault.” The error code was E7 on a Daikin VRV IV system — a generic communication error between the outdoor and indoor units. It sounds dramatic when every unit goes down at once, but it often has a simple cause.
In this case, a cleaner had accidentally knocked the power isolator for the outdoor unit while mopping the plant room floor. The outdoor unit lost power, the indoor units lost communication, and the entire system alarmed. We talked the FM through resetting the isolator over the phone. System came back online within ten minutes. No engineer visit needed.
Not every error code is that simple. But many are simpler than people think, and knowing what the code means before you call can save time, money, and unnecessary anxiety.
What VRV/VRF Error Codes Actually Mean
Error codes on VRV and VRF systems are the unit’s way of telling you what’s wrong — but they’re written in engineer shorthand, not plain English. Every manufacturer uses a different coding system:
- Daikin — alphanumeric codes (E0, E7, U4, L5, A3, etc.) displayed on the indoor unit’s LED or the centralised controller
- Mitsubishi Electric — alphanumeric codes with a letter-number format (E6, P8, U1, etc.) shown on the remote or City Multi controller
- Fujitsu — blinking LED patterns on the indoor unit combined with error codes on the remote controller
- Samsung — E-series codes on the DVM system controller
Common VRV/VRF Error Categories
Communication Errors (Daikin E7, U4; Mitsubishi E6)
The most common error type. The indoor and outdoor units communicate via a data cable, and when that communication breaks, everything stops. Causes include power interruption to the outdoor unit, a damaged or loose communication cable, water ingress into a junction box, or a failed PCB on one of the units. Sometimes a simple power cycle clears it. If it keeps coming back, there’s a wiring or hardware issue that needs investigation.
Refrigerant Circuit Errors (Daikin L5, L3; Mitsubishi P8)
These indicate a problem with the refrigerant system — low charge (leak), high discharge pressure (blocked condenser or overcharge), low suction pressure (restriction or low charge), or compressor protection activation. These are not DIY fixes. The system needs a qualified F-Gas engineer to diagnose and repair the refrigerant circuit.
Sensor Errors (Daikin A3, A1; Mitsubishi E1, E2)
Temperature and pressure sensors fail with age. The system detects an out-of-range or missing reading and shuts down to protect itself. Sensor replacement is straightforward for a trained engineer — it’s finding which of the potentially dozens of sensors has failed that takes the diagnostic skill.
What to Do When You See an Error Code
- Note the exact code — write down exactly what’s displayed, including any sub-codes or flashing patterns
- Check the obvious — is the outdoor unit powered on? Has a circuit breaker tripped? Has someone turned off an isolator?
- Try a power cycle — turn the system off at the isolator, wait 60 seconds, turn it back on. If the error clears and doesn’t return, it was likely a transient fault
- If it returns, call an engineer — recurring errors indicate a genuine fault that needs diagnosis. Give them the error code when you call — it helps us arrive with the right parts
When to Call Immediately
Some situations shouldn’t wait for a power cycle attempt: if you smell burning, if there’s a visible refrigerant leak (oil stains, hissing), if the outdoor unit is making an unusual grinding or rattling noise, or if the system is protecting a critical space like a server room. Call 020 3974 1419 — we attend VRV/VRF emergencies across London 24/7.