Strong smell from the AC vents

[SixPost]

All of the sudden, I'm getting a strong chemical smell out the vents when I have the AC on. Bad at first, then it fades after a few minutes of having the AC on. No smell if I don't have the AC on. The smell is that of lawn fertilizer... very much chemical. Could be coolant, but not exactly the coolant smell that I am familiar with. I know that mold and mildew can be an issue, but this doesn't smell like anything from nature... Any help in getting this figured out would be appreciated.

The heater core was suggested to me as a potential cause, but is it possible that that can happen so soon in a 2015 BMW?

I have also wondered about the coolant line leaks that some BMW V8s get in the hot V area of the engine. Anyone know the best way to see if these lines are leaking?

Many Thanks!