111r 54 plate air con recirculation switch

[wantalotus]

Hi guys, looking for a bit of a steer with the above. The air recirculation switch on my 111r appears to have stopped working. The tell tail light does not illuminate and nothing appears to happen when it is pressed. The ac works normally otherwise. A new switch is about £60 so I could do with having more than just a guess. Anybody else experienced this with any ideas would be greatly appreciated

[wantalotus]

Still looking for clues. Have seen a couple of used heater control units on ebay, but cannot work out where the ac and recirculation switches connect, and to which harness if at all. Any body got experience of this?
Thanks