A musty smell from the AC can mean mold in the drain pan, coil, or ducts

https://localhvacrepair680.brightsora.com/posts/how-to-diagnose-an-ac-running-not-cooling-without-delaying-repairs

A musty smell from the AC can mean mold in the drain pan, coil, or ducts. Check the filter, keep the area dry, and have the system cleaned by a technician.