What does a pollen filter actually do?
It sits in the air intake for the car's heating and ventilation system and filters the air that comes through the vents, catching pollen, dust, and general road grime before it reaches you inside the cabin. It's a different filter to the ones for the engine — this one is entirely about the air you breathe while driving, not how the engine runs.
How do you know it needs changing?
The two main signs are smell and airflow. A musty, stale smell from the vents, especially when the air con or heater first kicks in, is a classic sign the filter's saturated and starting to hold onto moisture and grime rather than catching it. Noticeably weaker airflow from the vents, even with the fan on full, is the other common sign — a clogged filter restricts how much air can get through at all.
Why does the air con smell musty specifically?
Moisture collects on the air con's cooling coil, and a clogged pollen filter sitting near it stops that area drying out properly between uses, which is exactly the damp, dark environment where odour-causing growth builds up. A fresh filter alone won't always fix a smell that's already set in, but it stops it getting any worse and is usually the first thing worth ruling out.
Is this covered in a normal service?
At ONEFIX, every service includes a written digital vehicle health check with photographs, and the pollen filter is one of the things checked as part of that — so if yours is due, it gets flagged with a photo rather than just a verbal mention you might forget by the time you're home.
Does it cost much to change?
It varies by car — some are a simple job behind the glovebox, others take longer because of where the manufacturer tucked it away. Rather than quote a figure that might not apply to your car, ONEFIX gives a written price before anything is done, so you know the actual cost for your own vehicle, not a rough average.
Can it wait until the next service?
If there's no smell and the airflow feels normal, there's usually no urgency, and it can be picked up at the next scheduled service without any issue. If the smell's already noticeable or the fan feels weaker than it used to, that's more of a "worth sorting now" situation than a "fine to leave" one.
Does where you drive make a difference?
Yes — driving mostly on dusty or gritty roads, or near fields and verges where pollen is heavier in spring and early summer, tends to clog a filter faster than motorway miles on a clean surface. Anyone doing a lot of short local trips around town will usually find it needs attention a little sooner than the handbook's mileage figure alone would suggest.
What's the quick way to check at home?
Run the fan on full with the air recirculation switched off and see if the airflow feels distinctly weaker than you remember, and take a sniff when the system first switches on from cold. Neither test is perfectly scientific, but together they're a reasonable clue as to whether it's worth asking to have it looked at properly.
The honest bottom line
A pollen filter is a small, inexpensive habit to stay on top of, and the cost of ignoring it is mostly comfort rather than anything serious. If you've noticed a smell or weaker airflow, mention it next time you book a service and ask for it to be checked as part of the health check.