Avant rear screen demister not working

[AndrewS1]

Morning all,

Relatively new to the world of Audis and have a couple of minor gremlins with what is otherwise a great car. In short, the rear screen demister doesn't work. Pressing the button on the climate control unit with the engine running causes the LED tell-tale to illumintae for a couple of seconds but it then switches off - much as it would with the ignition off. If I manually hold the button in, the heater does begin to cut through the condensation, so the circuit is basically healthy. It is as if a relay is failing to latch?!

Has anyone experienced anything similar?

All help appreciated.

Cheers,

Andrew S

[front wing]

As you say, sounds like the relay needs replacing. Believe it has a timer built in to turn off after a preset time of say around 10 minutes or something like.

[AndrewS1]

Update...

Took the car to a local VAG independent this afternoon. Apparently there is no relay - the demister is operated by a "Convenience Control Module" located on the floor of the car.

The verdict is that it is sensing a high resistance in the circuit and tripping. So, it could be a damaged or corroded wire pretty much anywhere in the circuit, or the control module itself...

To quote the technician, "it won't be an easy fix". Oh joy.

[kite]

Try cleaning the connectors on the CCM.
Is your passenger side floor damp !