Automatic cabin temperaure faulty?

[Hoops65]

I noticed this for the first time last week, but the automatic temperature control for the cabin seems to be out. The outside temperature was showing 17C and I has the setting on 21 as it is normally on but the blowers were blowing cold. When I changed the setting to 24 it seemed to settle down but did not feel like 24 in the car and does not leave much option if I need to go higher. Could it just be me or has anyone else had noticed this?

[Andy74]

My ten month old Superb is just going back in for the second time to get the air fixed. Mine just cuts out totally, you can hear it whirring but nothing coming from the blowers at all.

They replaced the motor driver previously a few weeks ago so we will see what they try this time.

This and a leaking windscreen has me a bit disappointed at the build quality from a brand new car.

[lowedb]

Rearding the original question: there are other factors than just the outside air temperature. There's a sun sensor too, so if the system thinks the sun is shining on you through the window, it will blow cooler air to compensate. If it's cloudy, it won't. At least that's how I think it works.

[wokwon]

If you can find someone with VCDS then they can read out the various sensor temperatures for you. With the old style 3 knob climatronic you could put it in diag mode which allowed you to read sensor values from the climatronic module itself. I don't know if you can do that with the new two-knob-and-lots-of-buttons clima unit.

Anyway the cabin temperature is sensed by the little shiny black round thingy about a quarter inch across near the clima buttons (marked as number 11 in the below diagram). Thats the only interior temperature sensor. To achieve dual zone, it just makes one side a bit cooler and one side a bit hotter but theres still only one sensor.

There are temperature sensors in the air box for each outlet (e.g. left face vent, centre face vent, right face vent, left foot vent etc etc). If you can get clima in diag mode, or use VCDS you can see the temperature sensor values and would notice if one was reading wrong.

Also with VCDS, you can perform an output test where it will cycle through moving each flap motor to see if any are jammed or have a failed servo.

There is a sunlight sensor at the front of the dash, just beneath the windscreen. It actually reads sunlight on each side so it can tell which side the sun is on and compensate for that side. It's not related to the sunlight sensor in the rear-vision mirror that is used for dimming mirrors and auto-headlights.

Finally, face vents will always be cooler than foot vents in heating mode as that is the way air is mixed in the system. The centre face vents are a blend of the left and right face vent air temperatures.

Basically, if you don't have access to VCDS and there is no diag mode on the new clima unit, i'd start by putting a cheap thermometer in the same position as the car's sensor and see if it gets close to your temperature setpoint.

Edited 11 June, 2012 by wokwon

[Hoops65]

Thanks for the help did not know it was so involved, very clever when it works !