Mitsubishi Heavy Industries Aircon Blinking Light Guide

MHI's Singapore residential range covers the Rocket, Deluxe and Exclusive families. Wall-mounted SRK units carry RUN and TIMER lamps, and some also have a power lamp. Newer models add a display, while older units rely on the lamp pattern alone.

Lamp position and colour vary by model. Some units label the lamps RUN and TIMER, while others use symbols. Match the pattern on your own unit before counting.

A steady RUN light shows normal running. A slow RUN blink usually indicates standby while the unit waits for a command. A short wait before the compressor starts is protection logic, not a fault.

Inverter models can pulse the RUN light during compressor ramp-up. The pulse settles once the room reaches the set temperature. Neither pattern needs a service call.

On units without a display, the RUN light counts first and the TIMER light counts second. The pair maps to a fault row in the handbook table. Watch two full cycles before deciding. Every row in that table also appears in the Mitsubishi Heavy Industries error code list.

Outdoor rows in the same table include E40 for a closed gas-side service valve, E36 for compressor overheat and E59 for outdoor-unit trouble. The same E-code can carry different board detail across MHI platforms. E14 is a platform-dependent row in the MHI tables, so record the reporting unit with the code.

On MHI units with a display, the panel or wired remote shows the E-code directly. Units with a wireless remote can also run a self-diagnosis from the handset. The manual for the exact model lists the button sequence.

Without a display, the RUN and TIMER pattern is the code. Write down both the pattern and any E-code shown. With several indoor heads, read the pattern from each one separately.

MHI multi-splits pair several SRK indoor heads with one SCM outdoor unit. Each head reports its own pattern independently, so the number of affected heads is the first clue.