Whenever I turn on my vents, which now it's A/C...I have to say...as disgusting as this sounds, it smells like a zoo (and I keep my car meticulously clean). What should I be checking?

 

It's the A/C evaporator that builds mold when it's used during winter time. Usually it's best to turn off the A/C a little before destination then blow some hot air to remove all humidity from the evaporator. Not much you can do about it now, because it's very hard to remove the evaporator for a cleaning. There are some chemical sprays available at various car dealers, with mixed results.

Try running the A/C for a while then before shutting off the engine, turn off the A/C then turn the heat to max and blow max air. Do this a couple of times, might help a little in the long run. It worked on my car, but the smell wasn't that strong.

 

When was the last time you changed your cabin filter?

 

Just a few months ago

 

You may want to check and clean the vents out. Maybe pull the heater core to make sure there is no build up in there and pull the fan and spray some Lysol or something in there.

 

Heater core is pretty new, did that around January time frame...will check though. This happens more in humid climate...I also tried turning a/c off a few minutes before shutting car down and that does seem to reduce/remove the smell the next time I start. I found the air filter was caked a bit already, plan on replacing that and cleaning area around it as it has lots of leaves built up (though drains looks clear).