Mitsubishi Heavy Industries Aircon Error Codes and Blinking Light Guide

Most MHI wall-mounted units in Singapore (SRK series, including SRK20 to SRK71 models) have two to three LEDs on the front panel. The operation light (green) shows running status. A timer light (orange) indicates timer function or flashes during faults. Some models include a separate power or standby indicator.

Newer MHI units with a display panel show E-prefix error codes directly (E1, E3, E6, etc.). Older SRK models without a display use LED blink counting — the operation and timer lights flash in a pattern that encodes the fault number.

MHI is a completely separate brand from Mitsubishi Electric (Starmex). The two brands use different error code systems, different parts, and different PCB designs. An E6 on an MHI unit means something different from an error on a Mitsubishi Electric unit. Always confirm which brand you have before looking up codes.

Before looking up codes, rule out the patterns that are part of normal operation. These are commonly mistaken for faults on MHI units.

A steady green operation light means the unit is running normally. A slow green blink means standby — the unit has power and is waiting for a command. The operation light staying on with no airflow for a few minutes after startup is normal compressor protection delay.

On inverter MHI models, the operation light may pulse slowly during the ramp-up period as the compressor adjusts speed. This is normal and stops once the unit reaches the set temperature.

On units with a display panel, MHI shows E-prefix codes directly (E1, E3, E6, E9, E32, etc.). The E is followed by one or two digits. Some models show the code on the indoor unit panel, while others show it on the wireless remote when the unit enters fault mode.

On older models without a display, the operation and timer lights blink in a counted pattern. The operation light encodes the tens digit and the timer light encodes the units digit. For example, 0 blinks on operation and 6 blinks on timer means E6.

Error codes persist in memory after power is removed. After a repair, the technician clears stored codes using the remote control or by shorting specific pins on the indoor PCB test connector.

Single-digit E codes cover communication failures and sensor errors. These are the most frequently seen codes on MHI units in Singapore. Communication codes (E1, E2) can sometimes clear after a power cycle, but recurring codes need wiring or PCB inspection.

Sensor codes (E3 to E9) almost always mean the thermistor has failed and needs replacement. These are straightforward repairs with readily available parts for most SRK models.

Two-digit E codes cover compressor protection, inverter module faults, and system-level protection triggers. These are more serious than sensor codes and almost always require a technician with diagnostic equipment.

E13 (compressor overcurrent) and E14 (high pressure protection) are common in Singapore. E13 can indicate a failing compressor or an electrical supply issue. E14 usually points to a dirty outdoor coil or restricted airflow around the outdoor unit. E32 (low pressure) often means the system has lost refrigerant through a leak.

MHI and Mitsubishi Electric are different companies with different product lines. Confusing the two is one of the most common mistakes when looking up error codes. Using the wrong brand's fault table leads to incorrect diagnosis.

MHI units are branded "Mitsubishi Heavy Industries" on the model sticker and use SRK (indoor) and SRC (outdoor) model numbers. Mitsubishi Electric units are branded "Mitsubishi Electric" and use MSY, MSZ, or MXY model numbers (Starmex branding in Singapore).

Error code formats also differ. MHI uses E-prefix codes (E1, E6, E32). Mitsubishi Electric uses a different alphanumeric system. If the model sticker says SRK, use this guide. If it says MSY, MSZ, or Starmex, use the Mitsubishi Electric guide instead.

On an MHI multi-split system (SCM outdoor unit with multiple SRK indoor units), each indoor unit has its own display or LED set. The error code appears on the specific indoor unit experiencing the fault.

If all indoor units show the same code or stop cooling at the same time, the outdoor unit is the likely source. Common shared-fault codes include E1 (communication), E14 (high pressure), and E32 (low pressure from refrigerant loss).

E31 (model mismatch) is specific to multi-split configurations. It triggers when an indoor unit is connected to an incompatible outdoor unit — usually after a partial replacement where only one component was changed.

For multi-split troubleshooting, check each indoor unit individually. If only one unit shows a code while the others run normally, the fault is isolated to that unit or its wiring connection.