Image by Ivydale via Flickr
When my 30 Amp AGA was fixed, the engineers from Spillers of Chard told me that the red switch on top of my AGA was to switch on the fan that vented all the smells etc from the AGA. Unlike on other AGAs where the smells etc go up the flue as the 30 Amp AGA doesn't have a flue you need to switch on the fan. So this was news to us! We've only had it for two and half years, oh well sometimes to can be ignorant. The reason I thought smells was coming out of the main oven door was because the door didn't fit properly. Apparently it was because I hadn't switched on the fan and it had nowhere else to go. So lovely all sorted now.
So for 30 Amp AGA cooker venting switch on the fan by pushing in the large red push button. For the 13 Amp I'm not sure what to do but it will have a similar arrangement as like the 30 Amp AGA the 13 Amp AGA has a pipe that goes outside to vent the smells. For all other AGAs it will go out the flue.Google+