5 Warning Signs
- Reduced airflow — the heater or AC blows weaker than usual, even on high.
- Musty smell — an unpleasant odour when you turn on the ventilation.
- Increased noise — the blower motor sounds louder as it works harder.
- Hay fever symptoms — increased sneezing or itchy eyes while driving.
- Foggy windscreen — the demister works poorly because airflow is restricted.
Recommended Intervals
Change every 12,000–15,000 miles or 12 months, whichever comes first. In high-pollen or urban areas, every 6 months is better. Some premium brands like BMW and Mercedes specify longer intervals (up to 20,000 miles) but shorter is always safer for air quality.
Frequently Asked Questions
Can a dirty cabin filter affect fuel economy?
Indirectly — if the filter is so clogged that the AC compressor works harder to maintain temperature, fuel consumption can increase slightly.
Is it worth changing the cabin filter before spring?
Absolutely. Fresh filters trap the most pollen when new. Changing in March gives you maximum protection for the worst of hay fever season (April-July).
