E270cdi classic estate misting up

[PHil G]

Anyone any ideas why after 3 years problem free ventilation my a/c seems incapable of keeping the screen clear of misting up in heavy rain? If the unit is run on rapid demist it keeps clear and if on manual all the air is directed to the screen it just about copes but on normal auto it mists.

 

[whitenemesis]

In "normal" is the a/c chiller off? i.e. econ mode?

 

[PHil G]

No the a/c chiller is on by default in normal auto

 

[whitenemesis]

Erm, don't think so! You can have the a/c in Econ mode whilst in auto.

The a/c is always comes on when you select demist though.

The othe possiblity is you need to have the system re-gased

 

[PHil G]

Thanks. No Econ button on the Classi unit . Only option on the dash is ac Off. On Auto does the chiller switch itself off? Had a ned condenser in front of cooling rad hence regas 9 month back. MB paid a %age of that outside warranttee as strange it stared leaking

 

[rf065]

If you had a leak 9 months ago, sounds as though you still have one.
Other possability is air con, although lit up on dash, will not work if outside temperature is near freezing.

Russ

 

[A-GALLY]

Try fitting a new pollen filter, my blower seemed very weak and a/c was not very good but after changing the filter the a/c and blower were much improved no probs keeping windows clear.

 

[jberks]

Pollen filter can do it as it restricts airflow.

When was the last time you gave the inside of the screen a thorough clean? That can have a massive effect. Moisture sticks to dirt and grease, maing it 10x harder for the demister to do it's thing. Screen mists up, people wipe with their hand rather than wait for the demister and that's it. Once the grease from your hand touches the screen, you're done for.

Unless the econ light is on, I'd imagine the aircon is fine and in any case, the gas level shouldn't have any effect on the dehumidifier aspect of the aircon system (I stand to be corrected on this one) , merely the cooling.

 

[whitenemesis]

The dehumidification is achieved by chilling the air, so gas level will affect the efficiency.

With the W203 system the a/c can be off (i.e. Econ mode) whilst in Auto mode. When pressing the screen demist button a/c will be forced on to dehumidify air and clear screen. a/c returns to previous state when demist is cancelled. I guess it's the same for your system.

 

[PHil G]

So the pollen filter sounds like a good thing to change to rule it out.
Where is it in the 2004 E Class Estate, and any tips on how to change?
Thanks for all comments so far!