A general question - why pollen filters?

[rmunns]

I can't really see why we need pollen filters in cars. What is the reason (other than a nice little earner for the dealers, etc.). OK, so you need a filter of some sort to protect the heater fan, ductwork and actuators, but why so fine? And why change every year? After all, we don't come equipped with pollen filters in nature and I, for one, don't walk around with one fitted to my face.

[Stickyfinger]

Regarding humans, we do have inbuilt pollen and fungal spore filters,

Nasal hairs, a damp and hair covered nasal cavity, a damp and micro hair covered set of "pipe work". Hairs in the larynx and the trachea "actively brush" fluids up to eject debris etc...without these layers of filters we we would all be dead in a week with fungal lung infections.

Run a car without the pollen filter and the car gets filthy....its best feature is the filtering of diesel particulates these days. As a hay fever sufferer I can assure you they work very well.

[GiveMeABreak]

I can't really see why we need pollen filters in cars. What is the reason (other than a nice little earner for the dealers, etc.). OK, so you need a filter of some sort to protect the heater fan, ductwork and actuators, but why so fine? And why change every year? After all, we don't come equipped with pollen filters in nature and I, for one, don't walk around with one fitted to my face.

Roger, it's not just for pollen as such, it is actually a carbon filter. It's purpose is to filter out pollutants from getting into the passenger cabin. The C5 X7 has built in air quality sensors that determine when the passenger air quality is poor and can activate the recycled air system accordingly. This can happen for example if stuck behind a bus or lorry in traffic, that is pumping out high levels of pollutants. You may not notice it but the air conditioning system changes the air to recycled until the car starts moving or the quality of air improves. The same is true when the car is put in reverse - again the recycling is activated to help prevent the car from sucking in exhaust fumes from your own car when reversing. Sometimes you can hear a change in noise in the heating system as this happens if you listen carefully. So to answer your question it is another system to try and improve passenger comfort and health and happens behind the scenes.

[JohnD]

The C5 X7 has built in air quality sensors The same is true when the car is put in reverse .

Thank you for that little gem. I wondered why every time I select reverse, my blower goes into overdrive.

[GiveMeABreak]

The system is automatic on models with dual zone automatic air conditioning. It doesn't work for bad smells not linked to pollutants (like a healthy dose of cow dung) or when it is below 5°C (to prevent the car potentially misting up), but a good idea, especially if you are an allergen sufferer!

[Old-Guy]

...its best feature is the filtering of diesel particulates these days. As a hay fever sufferer I can assure you they work very well.

I'm an occasional 'hay fever' sufferer (when thousands of acres of the Cotswold are a blaze of bright yellow oil-seed rape in full flower), 2013 was particularly bad. Coincidentally, we were running the blue VSX (RIP) at the time and once the choked and broken pollen filter was replaced, blessed relief ). Haven't had a recurrence since, and the Picasso has A/C .

[xantia_v6]

Funnily enough, the original reason that they were fitted was nothing to do with human breathing.

The air conditioning evaporator is constantly wet from condensation, and any pollen or other fine particles in the air tend to stick to it as fresh air blows past. These particles will form a coating on the evaporator fins and a sludge in the bottom of the evaporator casing which can eventually cause a significant reduction in cooling performance.

[Stickyfinger]

just like lungs without the natural protection then

[GiveMeABreak]

I always run an Air Con Bomb through mine at least once a year to sanitise the entire AC system, and have the Pollen filter replaced annually too. Every 2 years I have the AC system bled, sanitised and refilled to ensure the lurgies are kept at bay.

[rmunns]

Thanks for the interesting and educating replies. But I still feel £50 a year is a rip-off.

[mickeymoon]

£50 per year?? Change it yourself, they're cheap enough.

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[elma]

£50 is extortionate, I paid £12 for the one in the Scenic in Halfords.