Check that none of your fittings have corroded or rusted off...a leaking air hose can and will cause the compressor to keep running because it "thinks" the air springs are not full. The compressor has an auto shut off when it over heats which is what im assuming is wrong with yours. If you have a vag-com, scan it, if not, you can get a vag com to scan or take to an independent VW mechanic or the dealer.

 

Been there done that. My compressor had failed after the drivers side valve was leaking. Ignored by the previous owner.
I had to replace the compressor and after that the car raised up as normal but after a while the front sagged down again after leaving the TREG for a couple of days. Spray water on the valves.
The compressor and valves are relatively easy to replace. Make sure you check the fuse for the compressor as well. Mine was blown because the compressor wires corroded and shorted out.
Below is the link for valve replacement.

http://www.clubtouareg.com/forums/f44/how-to-replace-a-residual-pressure-valve-79332.html


Do not go to dealership for parts. If you need to buy locally rather than online buy Porshe parts. They are cheaper.

 

The inlet valve in the front air struts is a known point of failure. They corrode due to two different metals being used.

A dealer will often want to fit a new strut - HUGE cost.

Some dealers are better and will even drill out the corroded valve but there is a risk to this - do not get swarf in the strut!

There are couple of DIYs on here and various threads where people have been able to change the valve but you need to be VERY careful nothing gets into the strut.

Whatever you do when you've fixed it, and this goes for anyone else with air even if you do not have a problem at the moment, clean the inlets very carefully and then put a smear of any thick grease on them to prevent the corrosion. Repeat every spring and autumn.

 

Do anyone know where the fuse is and which number?

 

In a left hand drive treg it is under the left seat , easy to see it is a maxi fuse 40 amp I think from memory .
You should also probably change the relay as they often weld closed causing the compressor to run on and blow the fuse.
The relay is under the dash on drivers side LHD.
It is among a bunch of other relays but you can listen for the click when compressor kicks in to help locate it.
Hope this helps.

 

Correction to my post the reference to LHD is wrong my car Is RHD sorry has been a long day .

 

Now I have collected my car from the local dealership, and they did'nt find anything wrong. No condensation issue, noe feilue code, and the system is working. But it seems that they have upgraded the software, but no one knows what they have done.... Long live the official dealership of VW in Norway....

 

LOL glad its all sorted out!

 

Now It's back in a different garage, specialising in Audi / VAG systems.... Maybe faulty compressor running hot...

 

Today I got my treg back from the garage, and it was complete change of compressor unit. It ran hot, after 15-30 secs running the temp was approx 240 Celcius(464 F) and almost no air produced. So my thoughts is faulty compressor motor.

It was D&%!% expensive, but now the car is up and running again!

 

I'm glad it is all sorted out, hopefully no problems for a LONG time!! No intentions to rub it in but I am VERY glad I never went with air suspension the second time around....believe me, I waited 2 months for a treg with air and just gave up, im now glad I did.

Just trying to think here....but what swear starts with D?

 

With an unknown history on a used one you really don't know what you are getting into until after the sale. I was very lucky with my 04 in that it was good to me. I have had two major things on my '10, but was under warranty when they happened. Has also been very good to me. So to me it is luck of the draw.

 

Could not agree more! its is 100% LUCK!!!, any and every car is luck based. Some drive fords until they have well over 500000kms and some only get 60K kms.......just very random and also very annoying!

 

The swear word should be an F-word.... spelling mistake