PontiacBonnevilleClub.com

If that makes sense.

I was sitting in the car waiting on my wife and leaned towards the window and the air coming from the vent smelled wet and kinda musty.
Do I need to do an Evap core cleaning? or is there a leak somewhere letting air/water into the system?

Take a look under the car behind the passenger side front tire. With the AC running, the condensation coming off the evap coil should be dripping out of the car. If not, take a look under the HVAC box on the firewall. You are looking for a small hose or a hole in the underside of the box that lets the water drain out. If it gets plugged up, you can pick up mildew inside the box. If it gets too bad, it will start coming out the box inside the car and wetting down the passenger side carpet.

I noticed a wet spot on the groubnd with the A/C on the other day.

Perfectly normal for this water (condensate) to drip out when the A/C is running in warm humid weather.

You should turn off the A/C periodically to dry things out so the mold and mildew will not build up.
I didn't do that and it started to smell real bad one year.

What do you mean turn it off periodically? I turn it off before I get out, I usually don't leave it set on the A/C or MAX settings when I turn the car off. Or do you mean to drive the car without the A/C on a couple days a week?

I have had the kids in the car and it's been pretty hot and humid lately so I've been running it A LOT lately. I usually don't have the air on when I'm alone.

The dealer advised me many years ago to turn off the A/C for the last two minutes before you shut off the ignition and arrive at your destination. That usually gives it enough time to drain and dry out enough.

Hmmm I'll have to try that.