What is a Cabin Air Filter?
A pleated paper filter that cleans the air before it reaches the vents.
Simplified animation — not to scale.
In plain English
The cabin air filter — sometimes called a pollen filter — sits between the outside air intake and your dashboard vents. It traps dust, pollen, soot and leaves before they reach you, your screen demister or the air conditioning evaporator. It's a cheap part that makes a big difference to how the inside of the car smells and how well the heater and AC work.
"Like the filter on a vacuum cleaner — once it's clogged, nothing flows properly and everything starts to smell."
How it works
When the blower fan pulls air in from the grille at the base of the windscreen, it has to pass through the cabin filter first. The pleated filter media catches particles down to a few microns; higher-grade filters add an activated carbon layer that also absorbs odours and traffic fumes. As the filter blocks up, airflow drops, the fan has to work harder, and the evaporator gets dirty — which is where damp, musty smells usually start.
Signs of trouble
- ⚠Weak airflow from the vents even on full fan
- ⚠Musty or damp smell when heater or AC is on
- ⚠Windscreen takes longer to demist
- ⚠Visible dust or debris coming from the vents
- ⚠Hay-fever symptoms inside the car
£8–£95
Always get a written quote. Prices vary by car, region, and parts brand.