what does the air pump do in the mazda rx-7?

[avafan2005]

I have a 1988 mazda rx-7 and there was a squeeling noise coming from the belts so i started tightening them and noticed there all new belts! note: i just purchased the car 3 days ago. So all new belts just not adjusted properly and noticed that all the bolts and nuts were cross threaded whoever did this last was a idiot. Point is the adjuster bolt on the air pump belt torqued off and left the stud stuck inside so i could not put the air pump belt back on. There is no check engine light on there is no lights on indicating anything wrong and the car actually has better response on the throttle. no high idoling or low idol everything seems normal i just cant imagine they put that pump in for no reason any help would work. If all fails i will have to just have someone tap the broken screw out and replace it its just alot of shit to be removed and its a mazda there aint much room too work. thank you! honest answers only thanks.