When I buy a car - I spend a lot of time trying to get the small "right" for me - weird I know, but lots of smell absorber disks and frabrezze till I don;t notice any scent then I add my airfresheners.
Something I tried on my last one was this:
https://www.amazon.com/Armor-All-FRE...d+duct+cleaner
I was very surprised how well it worked and lasted several days. Now I did not have a musty smell that made me try it - I just saw it and tried it. I was impressed and it will be added to my tool bag for the next one.
Might be worth a shot? Cheap and easy to try anyway.