of the a/c system, of course.  i used to think that without that filter the evaporator in the dash would become caked in dust and become all mouldy,

after 5 years without the filter, i inspected the evaporator with a mirror, it is still pristine.

and i think it has less tendency to go mouldy, compared to those with filters fitted, as the evaporator will dry out faster as it is better able to breath the outside air.
 

i read  some (unsubstantiated) claims on websites that the filter is essential to protect the coils from dust, so why doesnt the heater matrix have one? thanks

I think the real purpose of the filter is to stop dust and pollen being drawn into the cabin from outside. That's why it is called a 'pollen filter' in the workshop manual and 'odour filter' in the service schedule. Way back in the old days when cars were real cars and not computers on wheels they didn't exist - they are a 'modern' feature!

I think with all the money and time Ford put into R&D then the air filter in the cabin should probably be there and has a job to do. The filter gets replaced annually and is dirty, if it's not there where does all that dirt go, it circulates around the car.

Don't hoover or dust the interior of the car for 5 years without the filter in and compare it to the same with a car that has a filter and see which is dirtier.

 

 

All modern vehicles have them.Replace it annually, & very easy to replace.They are very effective & capturing dust & pollen etc….

You know all those particulates that cars have been pumping out for years, wrecking human lungs, and are only recently getting trapped by DPFs & GPFs?  The pollen filter also helps to avoid breathing those while you're stuck in traffic...  

Back in my Peugeot days (duwing the war...  ) there were no pollen filters in the 306s.  Not fun for a hayfever sufferer.  And even less fun when someone did a 'funny' prank and dumped a load flour on my windscreen.  During the cleanup, some of it dropped into the scuttle and was then blown all over the interior through the vents.  Could also get entire live bugs (wasps in particular!) blowing right through the vents.  

If you chose the more expensive carbon filters, they also neutralise smells such as bin lorries and muck spreaders.

I remember one day opening the face vents on my fiat uno 55s whilst driving at speed , a huge mist of powdered dead leaves blew in my face and eyes so I couldn’t see. 

2 hours ago, isetta said:

on my fiat uno 55s whilst driving at speed

Was that going down hill with a strong tail wind ? 🤣

Actually it wasnt all that bad a car for the period. The ‘s’ meant it has a 5 speed box which did make it a lot more pleasant (and tinted glass). I managed to set it alight whilst mig welding the sill. Managed to put the fire out but after that it had fire damage to back door trim and back seat but still usable. 

I've always wondered if you replaced the standard filter with a K&N one, would it blow your face off, lol! 😄

BTW, K&N actually make reusable cabin filters for cars.

On 8/7/2022 at 9:47 AM, isetta said:

I remember one day opening the face vents on my fiat uno 55s whilst driving at speed , a huge mist of powdered dead leaves blew in my face and eyes so I couldn’t see. 

I can remember changing the filter on mine or parents Fabia and got a footwell full of dead leaves, so I was glad I had the filter to catch them all.