After posting this I tried it myself as I wasn't convinced it would work.. But I stood outside my car and the little fan on the central control for the air conditioning along with the temperature lights flash during its operation. My interpretation of this is that it's something you activate in a seasons of intense weather to either cool or defrost before getting in the car as there is clearly no 'OFF' setting, it just gets turned off when you turn on the ignition. Am I along the right lines?Ah ok, I'll try it out tomorrow. Thanks!