I get a funky smell from my AC all the time.
I researched this. Apparently it has do do with moisture from
condensation sitting in the AC components, which gathers
mildew, and then stinks like old socks.
The solution I've read about, was to install some sort of mini-fan
inside the AC components, that will run for a few minutes after the
engine turns off to evaporate out all the moisture.
I believe it was an aftermarket kit.
Sounded too hairy to me, so I live with the intermittent smell, for now...