For some reason whenever I turn on the A/C an old and stale smell come out of the vents. The air is cold so that's a plus but is there any way to eliminate that initial smell that comes out the vents?

 

if your car has a cabin filter try changing it.

 

What make and model is your car? We need some basic information to make a proper diagnosis.

 

Also it might help to know if it has been sitting awhile. Mine sat for a few years before I got back to using it.

 

1997 Saturn SL-2 160k miles
Daily Driver...commute about 70miles/day

 

The car is 13 years old and with out any additional information such as where you might live, the fact that it is in daily use sort of indicates that you do not need A/C much because mostly smells like that come from water collecting in the duct work combining with crud and making green stuff turn brown.
The drain for the Cabin A/C unit may have become plugged, not letting the water drain. That usually sticks through the fire wall some where. And no I don't know where never looked for mine, I just know it is there. That is why cars with A/C leave puddles of water on the road when they are parked, like an errant puppy before they are house trained.
Try passenger side-ish. If the A/C is draining then I would imagine spraying something like Fabreeze (spelling) to make the smell go away. Spray inside the cowl vents some where with the A/C running.
But standing water is probably the biggest problem.

 

Okay, cool. So I'll take a cool at this cabin filter ~thingamagig~ this weekend. Thanks guys

 

s- cars never had cabin filters

 

BUY

OZIUM

do what it tells you to do on the label

 

If you have not figured out where to buy this stuff, here is one suggestion;
Walmart; you need to look in the Auto/Car section with the air fresheners. It's a skinny blue can with a white cap.
For more, either ask, or check the internet.