noticed a fan/blower noise in engine compartment when stuck in traffic

[stumpjumper]

I've heard this twice now, both times stuck in traffic and idling in neutral, it goes on for a minute then goes off again, seems random to me :)

I'm just wondering what it is :)

(02 S, 6spd by the way)

[Loren]

Normal - secondary air pump cutting in to manage emissions.

[0586slb]

There's also a fan on in the right hand side air intake, that draws air in to cool the engine compartment. This one probably is more audible. Its more noticeable for us from England in the RHD cars. :)

[stumpjumper]

Normal - secondary air pump cutting in to manage emissions.

weird, I thought that only kicked in when the cats were cold, the only times I've heard this sound was when the engine was hot and I got stuck in traffic not moving so I thought it was something like what 0586slb mentioned

[deliriousga]

What 0586slb said. The engine compartment cooling fan kicks on and off depending on the temp and if the A/C compressor is on.