Mitsubishi Heavy — Faults, Diagnostics & Repair
Mid-tier Japanese brand found in many HDB and condo installs. SRK wall-mount units are reliable, but parts are less commonly stocked locally than Mitsubishi Electric or Daikin — older units may face longer repair lead times.
About Mitsubishi Heavy
Mitsubishi Heavy Industries (MHI) is a separate company from Mitsubishi Electric, though the shared name causes frequent confusion. MHI aircon units are a mid-range option in Singapore, offering solid build quality at a lower price point than the Starmex line. The SRK series is the most common residential model seen locally.
Solid mid-range option with good build quality from a reputable Japanese manufacturer. More affordable than Mitsubishi Electric, but with a thinner local parts supply and less technician familiarity in Singapore.
At a glance
Common Faults We Handle
The faults Mitsubishi Heavy owners bring to us most — and the ones our technicians know inside out.
E1/E3 sensor fault
Thermistor issues common in older units — triggers error codes related to room or coil temperature sensing.
Compressor lockout
Outdoor unit shuts down under high ambient load or due to refrigerant issues. Requires on-site diagnosis to isolate the cause.
Drainage blockage
Standard tropical humidity issue. Drain pan and line clogging causes water leaks — same pattern seen across all brands in Singapore.
PCB failure
Control board issues in units beyond 7-8 years. Parts sourcing for MHI boards may take longer than for more common brands.
Mitsubishi Heavy Diagnosis Cases
Real faults diagnosed on Mitsubishi Heavy units in Singapore — what we found and how it was resolved.
Diagnostic Tools
If your Mitsubishi Heavy is showing a code or blinking a pattern, use these tools to narrow the likely cause before calling anyone.
Where to find your model number
On SRK wall-mount units, the model sticker is typically inside the front panel — lift the panel and check the bottom-right area. For ceiling cassette units, the sticker is on the unit body behind the grille panel. The outdoor unit sticker is on the side panel, usually facing the wall or building ledge.
What We've Learned Servicing Mitsubishi Heavy
What Singapore owners ask about most, and what the diagnosis usually shows.
MHI and Mitsubishi Electric are completely separate companies with different parts, different error codes, and different service networks. Mixing up the brand leads to wrong parts being ordered.
Parts for MHI are less commonly stocked locally than Mitsubishi Electric. Repairs on older units may take longer if parts need to be sourced.
SRK series units are reliable but less familiar to many local technicians. Make sure whoever services it knows the MHI-specific fault codes.
Filter cleaning every 2-4 weeks as with any brand. MHI coils in high-humidity environments need chemical cleaning when airflow drops.
MHI units are a good mid-range option — the build quality is solid, but the weaker local support network is the main trade-off vs Mitsubishi Electric or Daikin.
Repair or Replace?
Age-based guidance for Mitsubishi Heavyunits. The right answer depends on the fault, the unit's age, and what the part costs.
Under 5 years
Repair is the right call. Faults at this age are typically minor — sensor issues, drainage, or installation-related problems.
5-8 years
Repair unless compressor or inverter board fails. Most faults at this age are still cost-effective to fix.
8-10 years
Weigh repair cost carefully. Parts sourcing delays for MHI components can make replacement more practical than waiting.
Over 10 years
Major component failures usually favour replacement. Parts availability drops and efficiency loss compounds the repair cost.
Maintenance Schedule
Staying on schedule prevents most of the faults listed above.
Popular Mitsubishi Heavy Models
The Mitsubishi Heavy series most common in Singapore HDB and condo installations.
SRK wall-mount
The main residential line seen in Singapore. Compact wall-mount units for bedrooms and living rooms in HDB and condo installs.
FDT/FDC ceiling cassette
Commercial and larger residential installs. Recessed ceiling units for open-plan spaces where wall mounting is not practical.
SCM multi-split
Multi-room residential systems. One outdoor unit serves multiple indoor units — used in larger flats and condos.
Need help with your Mitsubishi Heavy unit?
Send your model sticker and what changed. We'll advise the next diagnostic step before any work is approved.
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