Chemical smell coming from the AC vent

What is your question?

I do not notice the smell when the AC in not on; however, when I turn the AC on there is a chemical smell coming from the vents and I hear a sound as if the car is taking a deep breath when I accelerate. When I do not have the AC on I do not hear the sound.

What makes this problem better or worse?

this problem stops when AC is off.

How long has your 2010 Mitsubishi Galant had this problem?

2 weeks