Would duff AC cause steamy windows in the wet?

[Joelonghair]

So my AC decided to die at some point during the summer and I decided to leave it be for the time being as it is a cheap car (MK1 TT) and I could live with it.

Driving it today cross country in the horrendous weather we have been having it was a constant battle keeping the windows/windscreen from steaming up. I've not had this in the past so am assuming that the AC normally pulls the moisture out of the air but with just the heater function working this isn't the case? Am I on the right track?

If so any recommendations for AC diagnostic / repair in South Manchester? Whats the likely damage to the wallet?

Cheers in advance

[anonymous-user]

I am guessing that your car has a leak and the interior is wet. I would check the carpets and boot to see if they feel damp.

Every car I have ever owned with a serious condensation problem has let water in.

[Piersman2]

Using the air con will dry out the air in the car whether it's cold or hot blowing air.

So yes, that's why having a car with a defunct air con will mist up like a normal car of old!

[Joelonghair]

Thanks for confirming my suspicions.

There is no leaks per se (!) but the windows dont seem to be hitting their top positions so suspect this is letting some moisture in.

The joys of old German cars

[cuprabob]

Also, double check you've not got the climate control set to "recycle" as opposed to fresh air.

[ScoobyChris]

A/C could well be a factor. Certainly notice streaming windows when the temperature drops below 3 degrees and the air con is disabled.

Joelonghair said:

If so any recommendations for AC diagnostic / repair in South Manchester? Whats the likely damage to the wallet?

Worth getting the fault codes read using VAG-COM to rule out sensors but I know on similar vintage Octavias the clutch on the air con compressor fails stopping it engaging.

Chris

[Joelonghair]

Will give that a try tomorrow Cuprabob, I'm 99% certain it is on fresh air so if that can help then great.

[cuprabob]

Joelonghair said:

Will give that a try tomorrow Cuprabob, I'm 99% certain it is on fresh air so if that can help then great.

On the climate control you can access a "secret menu" which you can use to display data and fault codes relating to the climate control system which may help with diagnosis of the AC.
https://www.wak-tt.com/tt/climatecontcodes.htm

[Joelonghair]

Chris and Bob - great info thanks - will have a play in the morning.

[DonkeyApple]

Probably a damp car which the AC was dealing with rather than the AC being the cause.

[996Keef]

Take the mats up and check for dampness in the carpet. If it feels slightly damp it's likely to be wringing wet in the sound deadening

Only time I've had misty cars is when there's been a leak. Either tailgate seals, door rubbers, or I've had a plugged drain in the scuttle before now. Rear light seals as well. And a leaky windscreen seal caused it too.

There's a couple of ways to sort it. None are particularly quick or easy

You can rub chalk along the door seal and spray the car with water , the chalk will show where the seal isn't working.

Check the door seals for splits , holes etc. If in good nick you can treat them with gummi pflege to soften them up a bit.


You can pull the seats out and carpet up and dry them out but need to sort the leak first. it will take absolutely ages to dry out naturally. You could borrow a household dehumidifier and run it over a few days. Another good trick if the leak was only minor, is to put your heating on full, drive along and keep dropping your windows, it drags out the hot moist air. Wait for it to warm up inside again and repeat.

Hope some of that helps

[Joelonghair]

Thanks for the tips 995keef /donkeyapple!

I did about 5 hours driving today with the heater on full (directed at the screen) and the windows cracked half the time - did seem to improve towards the end such that I could turn the heat down to liveable levels.

Like most are alluding to there is probably multiple levels of b@ggery going on but the pointers certainly help so will work through them and see where I end up.

Apart from this it is still going strong so would be a shame to get rid.

Edited by Joelonghair on Friday 20th October 21:55

[996Keef]

No worries, I remembered after I posted that I had a car that had a wet cabin filter and it caused fogging , so I had a quick Google about TT's , seems they're known sometimes to have the scuttle panel drains block up and it wets the cabin filter.

Don't know how to link you but if you search for mk1 tt cabin filter wet , you should find some gen.

[smokey mow]

Joelonghair said:

Thanks for confirming my suspicions.

There is no leaks per se (!) but the windows dont seem to be hitting their top positions so suspect this is letting some moisture in.

The joys of old German cars

Sounds like you need to do a window reset so they park fully up. Not uncommon on a TT and easy to do.

Try this

Igntion on. Better with Car running.
Press and hold button all the way down.
When it hits the bottom stop. Release the button then press and hold it down again. Should hear a faint "click"
Manually hold all the way up.
When its fully up. Release and then press and hold UP again. Again a slight click.

[Snow and Rocks]

While it's definitely worth doing a thorough check for leaks I had an A6 that steamed up whenever you switched off the AC. To keep it clear without the AC you had to crank the fan right up.

There's not any unusual smells is there? Curry like smells along with steamy windows can indicate a leaking heater matrix.

[Joelonghair]

996keef - more homework for tomorrow before the rugby!

Smokey - thank you - and yes you are absolutely correct. I have had something similar before and did a reset which worked but the windows were then very obviously below top position. At the moment they 'close' and touch the rubbers but seems like they should be going another 5mm to complete the seal. Will attempt again tomorrow so fingers crossed.

Must say I do appreciate all the advice given on my steamy shed!

[Joelonghair]

Snow - there is a slight curry aroma but I think that is because it transported one home on Thursday - I've not noticed one otherwise

[the-norseman]

My car has the same issue, AC doesn't work and it steams up terribly. No damp carpets etc.

[Sheepshanks]

Snow and Rocks said:

While it's definitely worth doing a thorough check for leaks I had an A6 that steamed up whenever you switched off the AC.

Often that happens as the evaporator is wet with the a/c running so turning off the a/c just allows that wetness to be picked up and dumped into the cabin. A lot of cars turn the a/c down, rather than off, for around 15mins to try and dry the evaporator and then it goes off and the car suddenly steams up.

Having said that, I never used to use a/c unless I had to as it dried my contact lenses out - we've had some cars that just couldn't be driven in wet weather without misting up.

[DonkeyApple]

Joelonghair said:

Thanks for the tips 995keef /donkeyapple!

I did about 5 hours driving today with the heater on full (directed at the screen) and the windows cracked half the time - did seem to improve towards the end such that I could turn the heat down to liveable levels.

Like most are alluding to there is probably multiple levels of b@ggery going on but the pointers certainly help so will work through them and see where I end up.

Apart from this it is still going strong so would be a shame to get rid.

Edited by Joelonghair on Friday 20th October 21:55

In the old days it would usually be a leaking heater matrix that steamed a car up but these days they don't rot out like they used to. It's almost always damp in the car.

Depending on how old the car is there is a small chance that it's actually a blocked ac drain so condensate has been dripping into the footwell to wet the carpets.