I live near Dallas, and it’s very hot here now. About a week ago, I noticed a musty, funky smell when I got in the car. I had to open my windows AND put the A/C on high, recirculating off, to get the smell to go away. Then I would shut the windows and leave the A/C on open-air circulation. My husband sprayed Lysol in the air vents, but it didn’t really help. Any ideas out there?
Carefully check the carpet and trunk for damp areas. You might have a leak or plugged drain. Have you replaced the cabin air filter?
Check the cabin air filter and see if it is dirty. It could be the source of the odor. It should be replaced about every 20,000 miles. I’d do this first since it is a cheap fix. If it’s wet, you may have a problem with the outside air inlet for the passenger cabin.
my a/c smells musty thru the dash vents and air is routed thru the evap core. when i turn off a/c the dash vent air does not smell musty. i think the floor vents also smell ok when i am in heat mode. i think the hot coolant is always routed thru the heater core so that means the air is routed around the heater core when i have temp set to not-hot? ala blend door?
have you changed your cabin filter lately? It’s behind your glove box. Also , check for any debris build up in the cowl vents (between the hood and windshield)
Oh! Thank you very much for the information! How do we get behind the glove box?
I really appreciate your response; I got in the car today, and the smell was worse than ever.
Check the carpet on the floors, front and back. You could have a plugged condensation drain or leak from the rear window.
To get to the cabin filter look in your owners manual or look on YouTube.
Empty the glove compartment and take off the cover from the right side and back (one piece) grab the cabin filter and pull it out. stop using recirculate all the time, It promotes mold.
As mentioned, check the filter. Check the drain tubes and make sure it is not plugged. AC drain usually goes down the passenger side of the engine bay. I am sure there are youtube videos on how to change the cabin air filter.
After all that, I always turn the AC off one mile before I get home and let the fan run to get moisture out of the system. This has worked for me.
This odor is apparent when you open the car door and before you start the engine?
Sadly, yes it is. 
We did find the filter you mentioned— it was pitch black (never knew it was there before!) and are getting a new one today. But the filter doesn’t smell! So where is the smell actually coming from, any ideas??
Sounds like you have a water leak somewhere. Do you have a sunroof?
Remove your floor and trunk mats, press down on the carpet with a paper towel in all low locations, see if you find any water.
No, I don’t. But I do appreciate your input! 
Thank you. Will do!
Aha! I never thought of that! Will do that in the future, but still have to figure out how to get rid of the smell now! LOL!!!
WOW! What great suggestions from you guys! 
Doing that today!
Do you park outside, with leaves etc maybe plugging up the drains in frot of the windshield?
Thank you very much! Will look into this.