Aircon

[B5 BIKER]

My air on in a 2003 a6 won't let me activate the econ button.
as in, it is always lit up on the switch.
any one know what the reason would be,

 

[Shargo]

If the light in the button is lit it means the "Econ-mode" is active.
In some cases it can't be de-activated. AFAIK you need to connect a computer to see why.

The reason for this is either a fault or external cause (I don't remember if the AC lights up the Econ-mode whenn it's activated due to to low outside temp (like below freezing).
A common cause is to little cooling medium in the AC-system (low pressure).
I assume a faulty compressor could be causing it as well (including broken/slipping belt and faulty AC-clutch).

If you don't have access to VCDS or other means of checking the diagnostics try to see if the car activates the clutch when just started, this will IIRC give the more skilled AC-people (as in not me) a good hint where to go.

 

[B5 BIKER]

Cheers for that.
you can see from a previous post I was hearing a hissing noise when I turned the car off coming from the engine bay.
one of the other lads was of the opinion that this was normal, maybe not???
maybe I have a leak somewhere?
will have to refer to a specialist I feel

 

[TYphoon GB]

ECON light on all the time = low pressure.....almost certainly.

If you have history see if its been recharged in the last 5 years.
If not they all leak with age (about 100g a year if not used regularly).

If it is low pressure almost all the R134a has gone.

If you do have a leak its No1 cause is a stone chip in the condenser.
No2 is a duff pressure switch (bottom of the condenser LHS from the front)

Recharge may help but get some who does a gas pressure leak test not a Kwik Crap 'it holds a vacuum so its good' test.
These systems run up to 16 bar so a -1 bar test is pretty useless.

A recharge should cost around £50 - £75 by an independent or 'fridge guy'.

 

[B5 BIKER]

Cheers mate, it's going for a service next week so I will get it checked then