A/C on Sierra

[86chevyk10]

On my new to me 05' Sierra when I push the recirculate button on the a/c, I can still smell outside smells and it doesnt blow any harder. Ive had previous z71's that when the button is pushed, for some reason it begins to blow harder and clean air is recirculated throughout the cab. The a/c still blows cold, it just aggravates me having to smell someones running too damn rich POS in front of me....any suggestions of what could be wrong?

 

[doonjumper]

On my new to me 05' Sierra when I push the recirculate button on the a/c, I can still smell outside smells and it doesnt blow any harder. Ive had previous z71's that when the button is pushed, for some reason it begins to blow harder and clean air is recirculated throughout the cab. The a/c still blows cold, it just aggravates me having to smell someones running too damn rich POS in front of me....any suggestions of what could be wrong?

Vacum line could be off causing the vent door to stay open.