New noise ??

the fan draws in air from the cabin so that it passes over a temp sensor to tell the climate control what to do. you might have a build up of dust or something on the fan that can be vacuumed out.

Thanks everyone

I'm not sure why it got louder, but I will get the airline out and blow a bit of dust around.

I feel reassured that it's a normal thing and nothing to stress about.

Thanks again Andrew