ECON light won’t turn off

[Whodafunk]

I have a 2007 A3 8PA 2.0 TFSI Quattro

ECON light won’t turn off and I have no air con.

Scanned with VCDS and had a fault 00796 internal temp sensor, which is the fan behind the climate control unit. I changed that with a genuine new Audi part but it didn’t fix my problem.

Checked the air con pressure sensor and found moisture on the connector, so I changed that with a genuine Audi sensor but still no joy.

The air con clutch is spinning even with the climate control off. Is that normal?

Any ideas?

 

[Darren92]

is there gas in the system?

 

[Whodafunk]

Thinking that. How can I check?

 

[NHN]

The pulley will still turn, but it wont activate the compressor magnetic clutch until econ is turned off.

Quite a lot of local garages do regassing, try that.

 

[Whodafunk]

The pulley will still turn, but it wont activate the compressor magnetic clutch until econ is turned off.

Quite a lot of local garages do regassing, try that.

I understand the pulley will always turn when the aux belt is running (it has no other choice), however the internal part is spinning aswell. It does this even in ECON mode and even when the climate control is switched off

 

[Whodafunk]

So I’ve been doing some research and discovered a common fault with the compressor clutch assembly in that the bolt holding the plate comes loose and the spindle rounds off. This means the compressor spins freely with the pulley and air con doesn’t engage. I shall investigate tomorrow and remove the plate.

Useful video here

 

[traindweller]

Good find @Whodafunk, let us know how you get on and how easy it is to get to!

 

[Whodafunk]

Will do. I imagine it can be accessed from the front wheel arch with the lining removed. Hoping to do it in situ aswell which will make the task a hell of a lot easier

 

[marci4]

The 8P does not have a magnetic clutch on the compressor, it spins all the time even if ECON is on it just doesn't produce any pressure. These cars use variable displacement compressor and it is controlled from the AC Panel via N280 Regulator Valve. You might want to check the compressor you have as some of them fail very often.
Have you tried running basic settings on the climate control unit? I assume that after replacement of the fan the error went away?
Check if there is correct level of refrigerant in the system and climate panel is actually seeing that (via VCDS measurement blocks). Are your radiator fans ok?

 

[Whodafunk]

Ah that’s good to know, thank you.

When you mean basic settings from climate control do you mean via VCDS? Haven’t done that no, I’ll have a look.

How do you check refrigerant level, is that with a pressure gauge?

I assume my rad fans are ok, never had any over heating issues but I’ll check them too, thanks.

 

[marci4]

Ideally you'd check the refrigerant level with a pressure gauge (air con services have them) however it is also important to check if the pressure sensor is working correctly and to do this you need to go through climate control measuring blocks and somewhere in there you will have pressure in bars if I remember correctly.
To do Basic Settings you go into "08 auto HVAC", then "basic settings" and then "group 001", click "go" and you will hear the motors moving about.

If you do not have any errors related to rad fans that should be okay, the small one is failing quite often and in some cases the AC will refuse to turn on when that happens.

 

[Whodafunk]

Just looking at my fuse layout in engine bay.

F30 is meant to have a 20 amp fuse for Auxilary Heating but there is no fuse here.

There is however a 20 amp fuse in F3 which is meant to be vacant. I wonder if the previous owner or garage put it in the wrong place?

 

[Whodafunk]

Just an update on this one...

Checked again with VCDS and my compressor was off with shut off code 3: Refigerant pressure too low

Air con regassed and I now have ice cold air and the problem has been solved. Thanks for everyone’s help