Hi All,

 

Owner of a new to me Skoda Superb 2012 Elegance model. Purchased the car privately just under 4 weeks ago and so far covered nearly 2500 very enjoyable miles. Loving the car so far!

 

I’ve got a minor niggle and looking for some advice and guidance as I do not know VAG group cars well at all. But have always found forums a great community and asset in the past.

 

When I viewed the car I noticed the air con wasn’t as cold as I would like. The now previous owner advised the car had stood and probably needed a regas. I went against my better judgement and bought the car. Fast forward a couple of weeks and the newly found sunshine reminded me I need to get the car regassed. 

 

I took the car to be regassed and the garage went through the process taking just over an hour. The garage told me the system had too much gas in when they started, they had taken the old gas out and put new in to the correct level, but the air con was the same and appeared not to be working. They confirmed the system had no leaks and was keeping pressure. 

 

Leaving the garage feeling like I should have really pressed the issue of the air con further and kicking myself, I’m now looking to do any troubleshooting myself. 

 

So far i have:

-confirmed there’s gas in the system

-confirmed the system is keeping pressure

-checked the fuses in the door panel and under the bonnet

-scanned for fault codes (using Carista) - none showing for air con

 

Is there anything else i should look at to try and diagnose or prove where the fault in the system is?

 

I read on another thread (for an Octavia not Superb - unsure how different they are?) that the smaller rad fan in the engine bay should spin when the car is stationary to help cool the condenser - is this correct for the superb?

 

Any help appreciated :-)

 

Thanks

Get the vehicle connected to VCDS, check for any compressor shut down codes, if none then it will be a stuck pressure modulating solenoid, broken shear plate or stripped hub, I have experienced all of them on my unfortunate Octavia 2.

 

The latter 2 can be diagnosed with an angled inspection mirror while the engine is running with or without the AC switched on, the centre nut of the shaft should be rotating at all times.

 

Does either fan spin?

Thanks. I’ll see if I can find someone with VCDS to scan the car. I’d normally invest in a scan tool myself but the prices look quite high.

 

can any other tool access the codes?

On 06/06/2021 at 21:55, Wino said:

Does either fan spin?

No neither fan appears to spin when on the drive. 
 

I regularly do a 75 mile motorway run and the temp gauge always sits around 90 degrees. I can’t recall hearing the fan when I pull up after the run. 

 

Hi All,

 

I'm back :-)

 

I've had the car scanned with VCDS. A couple of minor historical faults were found that did not come back once cleared, and were not related to the AirCon.

 

Scan of the HVAC did not produce any faults either. 

 

I've pasted the log dump below - can anyone spot anything in the values that might push me in the right direction to finding the fault stopping the air con from working?

 

Thanks.

 

 

 

 IDE00019   Voltage terminal 30 14.0 V
  IDE00021   Engine speed 700 /min
  IDE00025   Coolant temperature 78 °C
  IDE00075   Vehicle speed 0 km/h
  IDE00198-ENG100282   Refrigerant pressure-MUX Kaeltemitteldruck 5.8 bar
  IDE00325   Diagnostic mode VW - diagnostic mode 
  IDE00767   No. of unscheduled ECU resets 255 
  IDE00965   Compressor shut-off requirement Compressor active: no shut-off condition is present 
  IDE00966   Compressor current: actual value 0.820 A
  IDE00967   Compressor current: specified value 0.820 A
  IDE00968   Compressor speed 900 /min
  IDE00969   Compressor load 1.7 Nm

  IDE00970-ENG103807   Coolant fan activation: actual value-MUX Lueftersteuerung 9.6 %
  IDE00971   Coolant fan activation: specified value 0.0 %
  IDE00972   Idle speed increase not active 
  IDE00973-ENG100004   Outside air temperature-MUX Temperatur 27.0 °C
  IDE00974-ENG100004   Outside air temperature internally calculated-MUX Temperatur 20.0 °C
  IDE00976   Left front vent temperature 23.7 °C
  IDE00977   Right front vent temperature 24.0 °C
  IDE00979-ENG101755   Left footwell vent temperature-MUX Ausblastemperatur 31.3 °C
  IDE00980   Right footwell vent temperature 28.7 °C
  IDE00982-ENG103939   Temperature after evaporator-MUX Temperatur nach Verdampfer 21.7 °C
  IDE00983   Interior temperature 27.1 °C
  IDE00984-ENG100238   Sun intensity left-MUX Insolation 0 W/m²

  IDE01419   Compressor shut-off condition: last Switch-off due to energy management 
  IDE01420   Compressor shut-off requirement: penultimate Shut-off from Engine Control Module (ECM) via CAN 
  IDE01421   Compressor shut-off requirement: antepenultimate Shut-off from Engine Control Module (ECM) via CAN 
  IDE02472   Air-conditioning operation information Cooling 

 

No compressor shut off codes and coolant fan not activated, high side pressure not raised sufficient to cool and trigger the fans, if raised at all, I dont have my charts but that may be the ambient pressure.

 

Its a classic case of the system thinking everything is OK but no refrigeration, it will be one of two things, the compressor modulating valve stuck or the shear plate sheared/splines on its hub stripped.

 

In the former the system pumps a little but cannot modulate the pressure, think of it like a broken pressure relief valve spring on an oil pump.

 

For the latter the controller believes that the pump is turning but it isn't, dont believe the compressor speed bull***t, it does not measure it, it is a calculated value just as is the compressor current which should read "modulating valve current" 820ma means it is getting a permanent signal waiting for the cooling to reach set temp (which it wont) at which stage it would modulate & display a lower current.

 

Check the high side pressure without the engine running, if its lower than the 5.8 bar then its the modulating valve, if its the same it could still be the valve stuck open but could equally be a shear plate/hub spline problem.

Edited 27 July, 20214 yr by J.R.