[Rednaxela]

I generally have my air con on most of the time, but I have found that if I turn it off mid journey, the windows steam up almost instantly.






As soon as switch it back on, the windows start to clear again.



Does the aircon unit have moisture inside it that gets blown into the car when you switch it off?



The car is as dry as a bone, so it must be something coming out of the vents.



whats occuring?

 

[AlanG]

I generally have my air con on most of the time, but I have found that if I turn it off mid journey, the windows steam up almost instantly.



 

As soon as switch it back on, the windows start to clear again.

 

Does the aircon unit have moisture inside it that gets blown into the car when you switch it off?

 

The car is as dry as a bone, so it must be something coming out of the vents.

 

whats occuring?

Have you checked all the footwells for water? Some people have had quite heavy water ingress.

 

[gary02tdi]

Alex, I drive with my A/C off all the time and never has this problem?
I know air con takes moisture out of the air.
In the morning i nip out and start Dug up! just to get the engine warmed up!
There for the heater is starting to heat him up!
Try this and see what happens.

 

[AlanG]

Alex, I drive with my A/C off all the time and never has this problem?
I know air con takes <span ="st">moisture out of the air.
In the morning i nip out and start Dug up! just to get the engine warmed up!
There for the heater is starting to heat him up!
Try this and see what happens.

</span>

Just take care that an unattended car with the keys in it renders your insurance void - effectively making your car uninsured. Not many people can afford to throw away £10k!Edited by: AlanG

 

[Rickenbacker]

If the air re-circulation is closed off it will always steam up with air con off this would be normal.

 

[Ashleytp]

I get this on my twingo too. If you don't use the aircon to de mist and wait for it to sort its self out slower it shouldn't start steaming up again.

 

[Rednaxela]

thanks for all your comments.

my drives to work are 20 mins max, so perhaps it never has time to dry out.

I will check the carpets at lunch time, but I think they are dry. The car lives in a garage overnight.



The recirculate is set to fresh air.

I will switch the air con off tonight and start up without it tomorrow. Perhaps it will dry overnight.

I notice that aircon's do tend to drip from under cars.

 

[ZillUp]

This is normal from the car. The aircon dries up the air inside the car and when it is switched off, any moisture that is in the heating system will instantly come out and steam up your windows (You might even notice a bit of a damp smell for a moment). If you wait for a while after switching it off and turn the heating up somewhat it will clear up and not cause the same issue until you switch on and off the aircon again.

I tend to keep my aircon off in normal conditions unless it is hot outside or really rainy (A/C works as a miracle for demisting the back windows!). Keeping it off will save you fuel too.


If you have a BMT you might notice especially warmer conditions that when the stop/start technology is engaged while waiting in traffic lights, the windows will start to steam up just because the aircon takes its power from the running engine.



Edited by: ZillUp

 

[Rednaxela]

Cool.. glad thats all it is.. many thanks
I do worry about leaving the aircon off though, as I was told it can cause the system to leak as the seals are not being lubricated by the fluid running around the system.

 

[luckyjimmy]

As other have mentioned, the windows will mist up for a short time when the A/C is turned off. This is normal behaviour and has been the same in ever car I've owned that has had A/C.

What you have to look for is condensation on the inside of the windows when the car has been parked for a while, particularly when it is colder outside. If this happens, look for wet carpets inside the car. This is how I first suspected leak(s) in my vehicle.

 

[Privatedoc]

Only car I've had that didn't do this was a 7 series BMW as it had a humidifier as well so a/c could be humidified and cooled, most a/c systems will dry the air too so as soon as the ac is off, moistuire returns and condenses on cool surfaces eg the window

 

[ducatikid]

Yes, it's odd the window fumes. my other car doesn't do that,but probably because I rarely turn the AC off.

I really like the car, great visibility in poor weather.

 

[Rednaxela]

If the air re-circulation is closed off it will always steam up with air con off this would be normal.

Opppps I checked my settings and the air was set to recirculate

Have changed it back now... It must have been like it for ages...

 

[AlanG]

But if you take in outside air laden with rain and spray, isn't that bringing in as much moisture as recirculating air laden with lung moisture?

 

[Rickenbacker]

No, it dosnt seem to work like that, not by the time the air had passes through the grill, pipes and cabin filter.

 

[bugbabe34]

I am confused about whether or not it's best to leave the air con on all the time or off and only on when needed.

After reading previous posts on here I have been leaving it on permanently, but reading some of the above, I'm now not sure.

 

[luckyjimmy]

I just turn the A/C on when I need it - either when it is warm (rare) or when the windows mist up (all the time with my wet carpets). I have not noticed any increase in fuel consumption when I've had the A/C on for longer periods. Just make sure you run it regularly to keep the system in tip top condition.

 

[Upmeister]

Having worked for an auto AC supplier in the past, the advice was always to keep the AC system switched on to gain the full benefits of having the system:
- in winter the dried air keeps the windows clear and keeps the driver fresher and more alert
It is also worth beraring in mind that keeping the system running reduces the long-term maintenance costs by ensuring the system lubricated and kept corrosion-free (extending compressor life)
As most systems shut-off automatically below 4 degrees, keeping it on year-round will not cause any other damage
To maintain maximum efficiency of the system (and minimise additional fuel usage) have the system checked and topped-up regularly - about 10% of the refringerant evaporates per annum

 

[GunSpeed]

Having worked for an auto AC supplier in the past, the advice was always to keep the AC system switched on to gain the full benefits of having the system:
- in winter the dried air keeps the windows clear and keeps the driver fresher and more alert
It is also worth beraring in mind that keeping the system running reduces the long-term maintenance costs by ensuring the system lubricated and kept corrosion-free (extending compressor life)
As most systems shut-off automatically below 4 degrees, keeping it on year-round will not cause any other damage
To maintain maximum efficiency of the system (and minimise additional fuel usage) have the system checked and topped-up regularly - about 10% of the refringerant evaporates per annum

+1

Only, I had no idea that the system is shut off below 4 degrees but it makes sence. I was just wondering if the dehumidifier is also shut down, what might explain in some cases the steamed up windows (but not always)

 

[SiJ2000]

The Ac is the dehumifier. Its just that th ac compressor shuts off at 4 degrees ambient...

I always leaave mine on... Never switched ac off ever in any car i have had...