Posted on Sep 7, 2026 by Sayasai

Mitsubishi Aircon

A Mitsubishi air conditioner is designed to provide cool and comfortable air, but sometimes it may start producing a bad smell. A musty, sour, or unpleasant odour coming from your aircon can make the room uncomfortable. It can also be a sign that dirt, moisture, mould, or other buildup has developed inside the unit.

If your Mitsubishi aircon smells bad, do not ignore the problem. Finding the cause early can help improve air quality and keep the system working properly.

Why Does a Mitsubishi Aircon Produce a Bad Smell?

There are several reasons why a Mitsubishi aircon may develop an unpleasant smell. The most common cause is dirt and moisture accumulating inside the indoor unit.

Air conditioners remove moisture from the air while operating. When moisture remains inside the unit, it can create a suitable environment for mould and bacteria to develop. Dust can also stick to the wet internal components, making the smell stronger over time.

A dirty air filter is another common reason. When filters become clogged with dust, the aircon may not circulate air properly and unpleasant odours can become noticeable.

Read more: 7 Tips to Maintain Daikin Aircon for a Long Lifespan – Servicing Guide Singapore

1. Dirty Air Filters

The air filter is one of the easiest components to check. It catches dust and particles before air enters the indoor unit.

If the filter becomes heavily covered with dust, airflow can become weaker, and the aircon may start producing a musty smell.

Remove and clean the filter according to the Mitsubishi model's instructions. Allow it to dry completely before putting it back.

Cleaning filters regularly is an important part of aircon general servicing and can help maintain better airflow.

2. Mould and Dirt Inside the Indoor Unit

If cleaning the filter does not remove the smell, there may be dirt or mould deeper inside the aircon.

Dust can accumulate on the evaporator coil, blower wheel, and other internal components. When these areas remain damp, unpleasant odours can develop.

In such situations, a professional aircon chemical wash may be useful. Chemical cleaning allows technicians to remove stubborn dirt and buildup from internal components that normal filter cleaning cannot reach.

For severely dirty units, an aircon chemical overhaul may be recommended for a more thorough cleaning.

3. Blocked or Dirty Drainage System

Your aircon produces condensation during normal operation. This water should flow through the drainage system and leave the indoor unit.

If the drain pipe or drain pan becomes dirty or partially blocked, water may remain inside the system. Stagnant water can contribute to bad smells and may also result in aircon water leaking.

Professional aircon servicing Singapore can include checking and cleaning the drainage system to help prevent these problems.

4. Bad Smell From the Outdoor Unit

Not every smell comes from the indoor unit. Sometimes debris, leaves, insects, or other contaminants around the outdoor condenser unit can contribute to unpleasant odours.

The outdoor unit should be kept clear of obstructions so that it can operate properly. However, avoid opening electrical components or attempting complicated cleaning yourself.

If you notice an unusual burning smell from the outdoor unit, switch off the aircon and arrange for professional inspection.

Can Aircon Servicing Remove the Bad Smell?

Yes, professional servicing can often help when the smell is caused by dirt, mould, dust, or drainage problems.

During servicing, a technician can inspect the indoor unit, clean accessible components, check the filters, examine the drainage system, and assess the overall condition of the aircon.

If the system is heavily contaminated, a chemical wash can provide deeper cleaning. However, the correct service depends on the condition of the unit.

Regular Aircon maintenance is especially useful in Singapore because air conditioners are frequently used throughout the year.

When Should You Call an Aircon Technician?

You should contact a professional if the bad smell continues after cleaning the filters or if the smell is accompanied by other problems.

These warning signs include:

• Aircon is not cold

• Weak airflow

• Water leaking from the indoor unit

• Strange noises

• Aircon light blinking

• Increasing electricity consumption

• Burning or electrical smell

If your Mitsubishi aircon is not cold, the problem may not be related to smell alone. A technician may need to inspect the evaporator coil, fan, refrigerant system, compressor, and other components. An aircon gas top-up should only be performed when low refrigerant is confirmed.

How LetsCool Aircon Can Help

If you are looking for the best aircon servicing in Singapore, LetsCool Aircon provides professional aircon maintenance and cleaning services for homes, offices, and other properties.

Whether your Mitsubishi aircon has a bad smell, weak airflow, poor cooling, or water leakage, proper inspection can help identify the actual cause. Depending on the condition of the unit, services such as general servicing, chemical wash, chemical overhaul, or aircon repair Singapore may be recommended.

Regular maintenance can also help prevent dirt buildup and keep your Mitsubishi aircon operating efficiently.

Final Thoughts

A bad smell from a Mitsubishi aircon is usually a sign that something needs attention. Dirty filters, mould, accumulated dust, moisture, and drainage problems are some of the most common causes.

Start by cleaning the air filters, but if the smell remains, professional servicing may be necessary. A chemical wash can be particularly helpful when dirt and mould have accumulated inside the indoor unit.

With regular aircon servicing Singapore and timely maintenance, you can keep your Mitsubishi aircon cleaner, fresher, and more comfortable for everyday use.

Aircon servicing Singapore

Aircon installation

11 Mandai Estate,

 #05-15 Eldix,

Singapore 729908

Mail ID: info@letscoolaircon.com.sg

Service -WhatsApp Call: +65 9862 3678 

Installation - WhatsApp Call: +65 94507178 

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