Replace the cabin filter if the aircond blows weaker than it used to at the same fan speed, smells musty or sour when you switch it on, takes longer to clear a fogged windscreen, sounds louder for the same airflow, or the filter looks grey and full of debris. Otherwise follow the interval in your service book.
What does the cabin filter do?
The cabin filter, also called the aircond filter, cleans the air that the air-conditioning fan blows into the car. Every bit of that air passes through it first, so it catches dust, pollen, leaves and fine particles before they reach the cabin.
Over time the filter fills up. Air finds it harder to get through, and dust that stays damp in the filter starts to smell. In Malaysia both happen faster than in a cooler, drier climate: haze and road dust load the filter, and the heat and humidity keep it damp.
The five signs
| Sign | What is going on | What to do |
|---|---|---|
| 1. Weaker airflow at the same fan speed | The filter is clogged, so less air gets through | Check the filter; replace if dirty |
| 2. Musty or sour smell when the aircond starts | Damp dust in the filter or on the evaporator behind it | Replace the filter; see the smell section below |
| 3. Windscreen takes longer to clear when it fogs | Less air reaches the demister vents | Check the filter |
| 4. The fan sounds louder for the same airflow | The fan is working harder to pull air through a blocked filter | Check the filter |
| 5. The filter looks grey or black, with leaves or debris | It is full | Replace it |
One sign on its own is worth a look. Two or more, and the filter is almost certainly due.
A weak aircond can also mean low refrigerant gas or a fan problem. Check the filter first: it is the simplest and most common cause, and a workshop will usually look there before recharging the gas.
Why does the aircond smell?
The cooling coil inside the aircond, the evaporator, is cold and wet whenever the aircond runs. Water condenses on it and drains out under the car. Dust that gets past a worn filter sticks to that wet surface. When the car is parked in the heat, that damp layer is where the musty, sour smell comes from.
A clogged filter adds to it in two ways: it holds damp dust itself, and once it is full it lets more dust through to the evaporator.
The DuraFit cabin filter pack lists Blocks PM2.5 Dust, Strong Airflow and Anti-Mould & Moisture Resistance. A fresh filter helps, but it can’t clean an evaporator that is already dirty. If the smell comes back within days of a new filter, ask a workshop to clean the evaporator.
A smell that is sweet and syrupy, like burning plastic, or like petrol is a different problem. Have the car checked by a workshop rather than changing the filter.
How do you check the filter yourself?
On most cars it takes about ten minutes and no tools:
- Empty the glovebox.
- Release the glovebox stops on each side (your owner’s manual shows how) and let it swing down.
- Unclip the filter cover and slide the filter out. Note the arrow showing which way the air flows.
- Hold it up to the light. Grey or black pleats, leaves or a damp smell mean it is time to replace it.
- Slide the new filter in with the arrow pointing the same way, then refit the cover and glovebox.
If your car has the filter somewhere harder to reach, or you’d rather not do it yourself, any ServAuto workshop can check and replace it while you wait.
How often should it be replaced?
Follow the interval in your car’s service book. Replace it sooner if you see any of the signs above, after weeks of haze, or if you often drive on dusty roads.
Finding the right filter
Cabin filters are made for specific cars. Look up yours in the DuraFit catalogue, or see all DuraFit cabin filters. Car not listed? Send the make, model and year to the ServAuto BD team on WhatsApp.
Frequently asked questions
Where is the cabin filter in my car?
Can I just clean the cabin filter instead of replacing it?
Will a new cabin filter get rid of a musty smell?
Which DuraFit cabin filter fits my car?
Sources
- Your vehicle's owner's manual and service book (cabin or air-conditioning filter location and replacement interval).
- DuraFit cabin filter packaging (pack claims quoted word for word).
- DuraFit catalogue: cabin filter part numbers and fitment, durafit.my/catalogue.
