Audi A3 2008 2.0tfsi air con stuck in Econ mode

[skypeller]

As the title

I bought the car privately about 6 weeks ago and it’s been brilliant especially since I’ve fitted Eibach springs and bbs ch wheels I’m really chuffed with it as a daily driver.

The previous owner mentioned he’d had a new or refurbed air con compressor fitted last year but I have noticed the air con obviously doesn’t work because it’s stuck in “econ” mode which I have read means it’s air con off mode, and won’t stay off when you try to select air con or air recirculating modes, which I was told means it’s refusing to run the compressor for Some reason - now I’ve had the air con system pressure checked at Kwik Fit and they said it’s more or less full or where it should be at least and that there’s probably a sensor fault but they can5 read the module or system for faults.
The air con pump clutch assembly looks new, however, the compressor looks original.

The pressure switch also doesn’t look as old as the pipe it’s attatched to but I’m thinking of buying a replacement air con pressure sensor anyway due to the high number of posts I’ve read where people have replaced this to fix their similar issues.

What other factors could their be to the air con not allowing the econ light to go out ?

Will I then need to reset the faults?

I assume the obd2 cable will somehow communicated with the air con module somehow through VCDS ?

Where is the best place to get VCDS and a cable? Is it difficult to use?

[Dr G]

AC not turning on does indeed mean it can't see pressure in the system and is refusing to engage the compressor to avoid damage.

Pressure switches are common-ish failures.

VCDS is made by Ross-Tech.

[gregpot2000]

if you have an Android phone, look into OBD 11 instead of VCDS. It's a lot cheaper, and can be kept with you all the time as it's a small wireless dongle that connects to your phone. Rather than a cumbersome laptop and cables to keep in the car.

I was an avid user of VCDS, but OBD11 does pretty much everything VCDS did for me, and in a more usable package

[skypeller]

Thanks for the replies and the sensor not seeing pressure - even though it’s there is looking like the most likely issue here. New sensor ordered should be here anytime now from GSF parts.

After replacing the sensor, Will I have to clear the fault on the a/c ecu before it begins to work do you know?

[skypeller]

Well, new sensor and still the same, do you know if the fault has to be cleared from the air con unit with VCDS / OBD11 etc before it will begin to work? What else could it be that is at fault?

[cuprabob]

Isn't there 2 sensors, a high pressure and a low pressure one?

If there is a code, it shouldn't need cleared to function correctly.

[skypeller]

I thought was was just one pressure switch ?

I am going to try disconnecting the air quality sensor and see if the Econ will turn off then and enable the air con compressor to run

[skypeller]

Well, just tried disconnecting the air quality sensor and that didn’t make it work either.... also tried blowing it with an air line and refitting and plugged it back in, no good.

Guess I need to get the codes read ... how much is vcds ? I’m guessing “lite” version won’t do any good here ?