Last weekend the AC stopped working in my 2015 vRS (TSI).  My local Skoda dealer couldn't even fit in a diagnostic check for 2 months so I took matters into my own hands.

 

VCDS shows the following fault codes:

263426 - Air Quality Sensor 
          B10AF 31 [009] - No Signal
          Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 3
                    Fault Frequency: 1
                    Reset counter: 134
                    Mileage: 63906 km
                    Date: 2019.05.18
                    Time: 17:06:23

                    Voltage terminal 30: 11.4 V
                    Outside air temperature: 24.0 °C
                    System run time-Engine running time: 0 s
                    System run time-Terminal 15 on: 3 s

262658 - High Pressure Sensor 
          B10AE 31 [009] - No Signal
          Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 134
                    Mileage: 63906 km
                    Date: 2019.05.18
                    Time: 17:06:20

                    Outside air temperature: 24.0 °C
                    Engine speed: 0 /min
                    Compressor current: actual value: 0.000 A
                    Temperature after evaporator: 26.3 °C
                    System run time-Engine running time: 0 s
                    System run time-Terminal 15 on: 0 s

 

Googling these fault codes reveals nothing useful, so it seems like this is a pretty rare fault.

 

Measuring blocks show the following:

 

 

After chatting with an Audi master tech mate of mine we came up with a theory.  The first fault won’t stop the AC from working but the second fault will, but as both happened together that suggests the two sensors are connected by a LIN bus network - if the AC pressure sensor has failed it may be outputting a scrappy LIN signal.  Furthermore 51 bar is the default value shown when the pressure sensor has failed, so that looks like the culprit.

 

Thankfully the pressure sensor is easily accessible in our engine bays, on the left side as you look in:

 

So I'm going to replace that, clear the fault codes and see if that restores the AC.  Watch this space!

 

If anyone else has had a similar experience I'd love to hear from you.

 

I seem to remember someone else on here having a failed air quality sensor, or maybe a corroded connection to the air quality sensor, not the sensor itself. So worth finding and unplugging to inspect contacts. Near pollen filter in scuttle area on his car, but can't remember what model that was.

 

As for the A/C, I think G65 sensor is quite a common failure.  There have been lots of superseding part numbers for this, suggesting an ongoing design battle.

I'd think replacement will get you going again.

Cool, thanks @Wino!

 

If replacing the pressure sensor doesn't clear both errors I'll track down the air quality sensor as well.

3 minutes ago, jaygemson said:

If replacing the pressure sensor doesn't clear both errors

I'd be very surprised if it cleared both.

48 minutes ago, Wino said:

I'd be very surprised if it cleared both.

 

Probably not, but the pressure sensor is the easiest to get to.

 

Would you happen to know if an air quality sensor failure would prevent the AC system from functioning by any chance?

Doubt it.

Pardon my intrusion, but does removing either of these sensors mean the refridgerant will escape?

 

Thanks

Stewart

The pressure sensor is a bit like a shrader tyre valve, so you can remove it from the line without discharing the system.

 

According to other threads I've read the air quality sensor is located by the main climate control air intake and not connected to the refridgerant system, so that can be replaced easily too.

8 minutes ago, jaygemson said:

The pressure sensor is a bit like a shrader tyre valve, so you can remove it from the line without discharing the system.

Removing a schrader valve from a tyre or A/C circuit will render them empty... probably an ambiguous comparison.

As for the faults, did you try erasing the error codes without replacing anypart just to be sure it wasn't something randomly transient?

34 minutes ago, RicardoM said:

Removing a schrader valve from a tyre or A/C circuit will render them empty... probably an ambiguous comparison.

 

You're right!  Reading that again it doesn't make sense, sorry.

 

What I meant was that, much like taking the pressure of a tyre, when you press the guage against the valve it opens and allows it to take a reading.  Then when you

remove it the valve seals shut.  The high pressure sensor on the AC system is the same - you can remove it and the valve closes, trapping the pressure in the system.

 

 

34 minutes ago, RicardoM said:

As for the faults, did you try erasing the error codes without replacing anypart just to be sure it wasn't something randomly transient?

 

I did indeed, several times.  No joy.

Fixed it!

 

The replacement high pressure sensor did nothing, so before calling in an AC specialist to check the system I thought I'd check the fuses.  Alas fuse 34 (7.5A) behind the glove box had blown!  This is responsible for powering a whole myriad of systems as well as the AC sensors  (TCS button, reverse light switch, dimming rear view mirror, start-stop button, ...) so it's hard to say what might've caused it, but I recall reading another thread where a faulty air quality sensor caused a fuse to blow, so I may need to replace that in the future.  In the meantime however I have air conditioning again, and boy am I happy ☺️

Great that you've fixed it, and told us how.  I'm feeling really bad though, for not suggesting the possibility of a shared fuse.

 

16 minutes ago, jaygemson said:

I recall reading another thread where a faulty air quality sensor caused a fuse to blow

 

Hopefully with more threads about, future problems that other members have with similar symptoms will have cheaper resolutions through 'crowd memory' or google, pointing to these info sources.

I think I read that same thread; shame my memory let me down.

Its amusing really as whenever you check the simplest and obvious thing first IE THE FUSE, Its never the damn fuse.