Air pump noise

[fireman32_14]

Had a pretty good snow storm here today in Pennsylvania .. This is the first chance I've got to drive the trailblazer in the snow, I'm quite impressed in how well it did, anyway whenever I start it I can hear the air pump running for a few seconds then speeding up and finally shutting down, is it normal for me to hear this? Or is something wrong? I have no codes btw

 

[Wooluf1952]

That sounds like the Secondary Air Injection system, but it should only kick in at cold start-ups.
Does it happen even when the engine is warm?

 

[fireman32_14]

No it only happens when cold, i was just wondering if it was normal for me to hear it

 

[The_Roadie]

The shop vac noise is totally expected.

 

[fireman32_14]

Ok good that makes me feel better, thanks!