Musty smell

My 2002 PT Cruiser started having a musty smell in the last two weeks. It comes out of the vents. It hasn’t been flooded - no water damage, nothing spilled in it. Nothing is leaking. Any suggestions?

Clean out the drain tube that goes to the evaparator, it’s under the right side of the cowl. Remove the cabin air filter and spray a deodorant/disinfectant made for car a/c vent systems sold at Advance or Auto Zone with the a/c on high.
The problem is mold in the vents.

Thanks!