elddis autoquest winterpack

hi there,

i have an elddis autoquest 145 2012 model, we bought it with a winterpack fitted, can anyone tell me how this works, there is a switch below the thermostat which has a red neon indicator in it but when you switch it on it does not illuminate, can you tell me if this is the switch and does it only work below a certain temperature and what is that temperature, if this is the case is it worth just leaving it switched on?

cheers,