With modern ovens generally, you'll find that the function you select may use any combination of elements even though it might not make sense for what you've selected on the function dial.
For example, some ovens, regardless of the function you've chosen will turn on every element in the product for the pre-heat cycle to get it up to temperature then turn them off, and that's normally why most recipes say to pre-heat your oven before putting the food in, otherwise if your oven bangs the grill element on full chat in the pre-heat phase you can get a lot of ruined food loads.
Fan element being small compared to grill is normal, is your fan element a single coil or multiple?
With modern ovens generally, you'll find that the function you select may use any combination of elements even though it might not make sense for what you've selected on the function dial.
For example, some ovens, regardless of the function you've chosen will turn on every element in the product for the pre-heat cycle to get it up to temperature then turn them off, and that's normally why most recipes say to pre-heat your oven before putting the food in, otherwise if your oven bangs the grill element on full chat in the pre-heat phase you can get a lot of ruined food loads.
Fan element being small compared to grill is normal, is your fan element a single coil or multiple?