What Am I Doing Wrong?

[Keithuk]

Only my windscreen mists up but the A/C on the screen clears it quickly.

[darrent]

I hope you're not referring to my post being illegible

No complaint on my part, merely pointing out to the OP that sometimes you get a freak mix of conditions that creates instant condensation and air con makes this type of situation worse, hence why it was switched off.  I can live with the odd bit of condensation 

No mate not yours  I've never had this mix of conditions. Any condensation/misting I get on the windscreen is cleared pretty much straight away once I divert the air to it, air con on 

[Neil gti]

Switch air on on
It clears in seconds

[golfhappy]

What am I missing here? Two complaints about cars steaming up and neither have the air con switched on, to be fair though one of the posts is hardly legible. Try switching it on ya tight buggers 

  Darn it, it's mine! That bloody college that i gave £500 for a English gcse must have been one of those fake ones! Well £503 in total that A4 frame frae Asda!!

[jonesltd]

Ac on or off then as some saying on others off?

[dubber36]

On. It dehumidifies as well as chilling the air. Mine is on all day everyday.

[mustard]

I was reading through an old VW Driver magazine and there was a letter from someone who was experiencing similar problems. In his case it was diagnosed as a problem with the fresh air inlet servo. He removed the pollen filter and could see the flap opening and closing without any input from the air con.

He got a dealer to 'reset the parameters of the servo's potentiometer' and this cured it.

The article is in the February 2010 issue.

[Mattyj]

I'm surprised no one has mentioned that your car could be damp inside which is causing the mist up i had it in my fabia the door seals were blown had a little in mk6 the rear wash wiper pipe was split getting internals wet there is a guide to repair this if needed made by some outstanding bloke 

[dubber36]

I was reading through an old VW Driver magazine and there was a letter from someone who was experiencing similar problems. In his case it was diagnosed as a problem with the fresh air inlet servo. He removed the pollen filter and could see the flap opening and closing without any input from the air con.

He got a dealer to 'reset the parameters of the servo's potentiometer' and this cured it.

The article is in the February 2010 issue.

That may well have been me. I'll dig the magazine out and have a look.

Either way, the 'fix' only worked for a short time. It was a common fault on B5.5 Passats. The only 100% cure was to replace the servo, but this was a dash out job and a price of £900 from the dealer. Many people just wedged the flap permanently open with a stick.

[Big_Dave]

Flick the A/C on, it'll clear pretty much instantly. Only in town/stop start traffic do you use more fuel with it on, at any half-cruising speed the extra usage is negligible. 

Bare in mind, that when A/C is in use it creates a lot of condensation (hence the drip under the car). The internals of the system also get damp, so when you switch the a/c off, that dampness is blown into the car.

To dry the system properly if it's bothering you, have the blowers on full heat for 5 mins with a/c on, then switch a/c off and it should cure the phantom misting up.

However, if you bring some dampness in the car, or even if it rains whilst driving it will always start to get damp inside. Cars are sealed incredibly well now, so the damp air through the vents when it's raining stays in the car.