Audi S3 8P Undertray Wet Patch, What Is It?

[HHS3]

Hello,

I looked under the car a few weeks back and saw this small wet patch underneath the drivers side foot-well area, the photos attached were taken yesterday of which the patch hasn't got any larger or smaller since I first saw it.

I'm not loosing any coolant or oil (to the best of my knowledge) and had the cambelt and waterpump done last year, I also can't see any leaks in the engine bay. It's a slightly sticky residue so I'm just trying to decipher what it actually is and should I get it check out?

Thanks.

 

[Cornish John]

Air con perhaps?

 

[HHS3]

Good shout, I had the whole compressor replaced last year and if I remember correctly, then when the ECON button is stuck on (which it is again now), then that means there's a fault with the air con somewhere. I started noticing that the ECON button was staying on around about the same time I first saw this actually, so I'll take it back to Storm Devs and get them to have a look at it.

Also, is it true that if you don't use the air con for several months then it will need to be re-gassed? As I haven't used it once since getting the air con compressor & gas replaced last year.

 

[Cornish John]

It is always worth remembering, you will always get a wet patch from the air con during normal operation.
I get mine checked every two years, just as a matter of course. Only just had mine checked six weeks ago, all good.
So always good to be on the safe side!

I have never had to have mine re-gassed, mine is a 2010 plate, I bought it at one year old.
Now done 223,000 miles, no air con problems.

Normally it needs a re-gas after a repair/leak/split hose etc.

Also regular changing of the cabin filter, helps with operation and smells!

 

[HHS3]

Cool thanks for the info mate, I'll report back once it's been in.

 

[Nessy]

Also, is it true that if you don't use the air con for several months then it will need to be re-gassed? As I haven't used it once since getting the air con compressor & gas replaced last year.

I've always been led to believe that the refrigerant gas in the air-con system also lubricates the seals in the pipework and stops them drying out , which can cause the gas to escape.
To stop this they recommend that air-con systems be run for at least 10 minutes per week so that the seals are lubricated and stay supple.
I don't know if this really is true, but I've always done it on the basis that it can do no harm, and probably will do a lot of good!

 

[HHS3]

I've always been led to believe that the refrigerant gas in the air-con system also lubricates the seals in the pipework and stops them drying out , which can cause the gas to escape.
To stop this they recommend that air-con systems be run for at least 10 minutes per week so that the seals are lubricated and stay supple.
I don't know if this really is true, but I've always done it on the basis that it can do no harm, and probably will do a lot of good!

That's handy to know thanks mate. Guess I'll start getting into the routine of running it for a short period of time regularly then to help prevent any potential issues.

 

[SootySport]

I've always been led to believe that the refrigerant gas in the air-con system also lubricates the seals in the pipework and stops them drying out , which can cause the gas to escape.
To stop this they recommend that air-con systems be run for at least 10 minutes per week so that the seals are lubricated and stay supple.
I don't know if this really is true, but I've always done it on the basis that it can do no harm, and probably will do a lot of good!

That's handy to know thanks mate. Guess I'll start getting into the routine of running it for a short period of time regularly then to help prevent any potential issues.

Abolutely right Nessy. It's a case of use it or loose it. Some people have the idea that using a/c increases fuel consumption, whilst that is true if you drive with windows open you also burn more fuel so you can't win either way, may as well be cool and comfortable. It is also worth using in the winter on those cold rainy days when the inside of the windows steam up, the a/c is also a de-humidifier and will operate with the heater at any temperature you choose. The a/c system in our Audis is actually call Climate Control for these reasons, not to just cool the air in the car. The a/c is always on in our car all year round, only setting that changes is the temperature now and again.
You should have two little pools of water under the car if your a/c is working correctly, there are two drain tubes.

 

[HHS3]

Abolutely right Nessy. It's a case of use it or loose it. Some people have the idea that using a/c increases fuel consumption, whilst that is true if you drive with windows open you also burn more fuel so you can't win either way, may as well be cool and comfortable. It is also worth using in the winter on those cold rainy days when the inside of the windows steam up, the a/c is also a de-humidifier and will operate with the heater at any temperature you choose. The a/c system in our Audis is actually call Climate Control for these reasons, not to just cool the air in the car. The a/c is always on in our car all year round, only setting that changes is the temperature now and again.
You should have two little pools of water under the car if your a/c is working correctly, there are two drain tubes.

Ah I see, didn't know this was genuinely the case so lesson learnt there then. The only time I had previously used the air con in my two years of ownership was in winter to de-humidify the windscreen, hence why it's gone kaput in both summers I guess!

Good to know thanks, I've got it booked into Storm tomorrow as my air-con at least needs a re-gas because the ECON button is permanently on.