You switch on the aircond, and the first thing that reaches you is a damp, musty smell — a problem many Malaysian households know all too well.
Here's the direct answer: the root cause is almost always mould growing inside the aircond. Malaysia's year-round humidity of 70-85%, combined with the moisture and dust that build up inside the unit, creates ideal conditions for mould. Once it settles on the evaporator and blower, every start-up carries that smell straight into the room.
The good news — this can be fixed, and prevented. This guide covers it in three steps:
● Where the smell comes from — finding the root cause so the fix actually works
● How to fix it now — getting rid of the smell first
● How to prevent it — using deep self-cleaning to keep it from coming back
Where the Musty Smell Comes From
The way an aircond cools a room naturally creates a damp, dark environment inside the unit.
During cooling, moisture in the air condenses on the evaporator surface — that's normal. But after the unit switches off, if that moisture stays inside, and dust keeps building up on the filter and evaporator, mould gets both the water and the surface it needs to grow steadily inside the machine.
In Malaysia's year-round humid climate, this happens much faster than in temperate regions — typically within 3-6 months of regular use, the musty smell starts to appear.
Beyond the smell, internal dust and mould bring two more problems: weaker airflow and slower cooling (dust blocks the air path), and electricity use climbing by 10-20% (the unit has to work harder to deliver the same cooling).
So a musty smell isn't just an odour issue — it's a direct signal that the inside of the aircond needs cleaning.
How to Fix It Now
If the smell is already there, work through these steps in order:
Step 1: Wash the filter
Remove the filter, rinse it with water, let it dry completely, and put it back. The filter collects dust faster than any other part, and it's the easiest to handle yourself. For a mild musty smell, a clean filter alone often brings a noticeable improvement.
Step 2: Run a deep self-cleaning cycle
If your aircond has a self-cleaning function, run a full cycle after washing the filter — this handles the evaporator surface that the filter can't cover.
Self-cleaning depth varies a lot between brands. Basic versions simply blow-dry the interior after shutdown; deeper systems — like Comfee's Active Clean+ — use a physical "condense → frost → rinse → dry" process to lift the entire layer of dust and bacteria off the evaporator and flush it away.
Step 3: If the smell is severe, book a professional cleaning
If the smell is strong, or the unit hasn't had professional servicing in over a year, a chemical wash is worth arranging — typically RM80-150 per unit in Malaysia.
A technician will thoroughly clean the deeper components: the evaporator, blower wheel, and drainage pipe.
How Active Clean+ Keeps the Smell From Coming Back
Once the smell is dealt with, the more important part is making sure it doesn't return. The principle is simple: don't let the inside of the aircond stay damp and dusty for long periods.
Make deep self-cleaning a routine
Rather than waiting for the smell to reappear, let the aircond clean itself regularly.
That's exactly what Active Clean+ on the Comfee Gusto Series is designed for — one tap in the SmartHome App starts a 42-minute, 4-step deep cleaning cycle that runs automatically:
Step 1: Condensation (10 minutes) — the aircond runs in cooling mode at medium fan speed, letting moisture condense naturally on the evaporator surface to soften the layer of dust sitting on it.
Step 2: Frosting (10 minutes) — the temperature drops rapidly to below -10°C, freezing dust and bacteria into a layer of frost — physically separating them from the metal fins.
Step 3: Rinsing (20 minutes) — the frost melts into water, flushing away the loosened dust and bacteria in one go — including the stubborn build-up that a basic water-rinse self-clean can't remove.
Step 4: Drying (2 minutes) — the evaporator dries completely. This final step matters most for preventing musty smells — with no moisture left behind, mould has no environment to grow in, and the next start-up delivers clean, fresh air.
Compared with basic "blow-dry after shutdown" self-cleaning, this frost-and-melt process reaches the deep build-up attached to the evaporator — which is precisely where recurring musty smells come from.
To learn more about how Active Clean+ protects your home's air quality over the long term, read our detailed guide: Healthy Air at Home: How Comfee Gusto Pro Helps Keep Your Aircond Clean in Malaysia.
For most households, running it once every 2-4 weeks is enough; homes that run the aircond for long hours daily can do it weekly.
Add a continuous layer of air protection
Beyond Active Clean+, the Comfee Gusto Pro adds Ion Sterilization — releasing negative ions that continuously suppress airborne bacteria, so protection isn't limited to the 42 minutes of the cleaning cycle.
Keep humidity under control
Mould depends on moisture, so managing humidity cuts off its growing conditions at the source.
The Gusto Series' AI Humidity Control automatically holds indoor humidity within the comfortable 40-70% range — the room stays dry, the unit's internal moisture load drops, and the room feels 2-3°C cooler than the actual setting.
Keep the yearly professional service
Self-cleaning handles the day-to-day; professional servicing handles the deeper components.
They work together rather than replace each other. With deep self-cleaning in place, professional washes can be needed far less often — but a yearly check is still worth keeping.
An Aircond That Keeps Itself Clean
Back to the original question — what do you do about a musty aircond smell?
In the short term, cleaning fixes it. In the long term, prevention keeps it away — and an aircond that keeps itself clean does most of that work for you.
The Comfee Gusto Series turns musty-smell prevention into an automated routine:
● Active Clean+ — a 42-minute, 4-step deep self-cleaning cycle, started with one tap, physically lifting dust and bacteria off the evaporator
● Ion Sterilization (Gusto Pro exclusive) — continuous air protection between cleaning cycles
● AI Humidity Control — humidity locked at 40-70%, reducing mould's growing conditions at the source
● 3-year general + 5-year compressor warranty — long-term peace of mind
From then on, what comes out at start-up is clean, cool air — not months of accumulated mustiness.
Available through Comfee Malaysia's authorised channels: the Comfee Malaysia Official Store on Shopee, the Comfee Official Store on Lazada, and Comfee Malaysia on TikTok Shop — or visit the Comfee Malaysia official website for more details.
FAQ About Musty Aircond Smell in Malaysia
Q1: Why does my aircond smell musty every time I switch it on?
The root cause is almost always mould growing inside the unit — Malaysia's 70-85% humidity, combined with internal dust and leftover moisture from cooling, lets mould grow on the evaporator and blower. The airflow carries the smell into the room at start-up.
Q2: Is a musty aircond smell bad for health?
A musty smell means the air is passing through an environment where mould and bacteria are growing. The impact is more noticeable for households with young children, elderly members, or anyone with respiratory sensitivity — it's worth addressing promptly rather than ignoring.
Q3: Will washing the filter get rid of the smell?
For mild cases, yes — noticeably. But the filter is only the first layer. Mould on the evaporator and blower needs deep self-cleaning or professional servicing to remove.
Q4: Does self-cleaning actually work?
Yes — the key is cleaning depth. Basic self-cleaning simply dries the interior; Comfee's Active Clean+ uses a frost-and-melt physical process to lift build-up off the evaporator, completing a deep clean in 42 minutes and significantly delaying the smell's return.
Q5: Do I still need a chemical wash if my aircond has self-cleaning?
Yes, but far less often. Self-cleaning handles day-to-day maintenance; professional washes handle deeper components like the blower wheel and drainage pipe — a yearly service is still recommended.
Q6: How often should I run Active Clean+?
Once every 2-4 weeks for typical households; weekly for homes running the aircond long hours daily. It starts with one tap in the SmartHome App.
Q7: How do I prevent musty aircond smells at the source?
Three things: regular deep self-cleaning (so dust never accumulates), indoor humidity control (Comfee's AI Humidity Control locks it at 40-70%), and a yearly professional service. Together, these keep the smell from coming back.