There is a door that separates the two units, but there is still some noise transfer.In the past I've used this product to provide some acoustic separation, but the company no longer sells it and I haven't found another supplier.https://www.amazon.ca/Conditioner-Windshield-Waterproof-Soundproof-Panel-Gray/dp/B07L3M8KH5/ref=asc_df_B07L3M8KH5/?

For our STRs, VRBO and AIR collect from the guests and pay the State

(We are getting requests  from people wanting to rent as off platform guests and want something to show them other than directing them to VRBO or AIR.)Appreciate any advice.

This is why assumable loans get so little air time. 

@Greg Scott So I had a technician go out because tenant says the air wasn't working.

I want a duplex that I will live in Half and air bnb the other to limit my expenses  

The best way to do this is to go on VRBO and Air and look at what your competitors are doing in the areas you're considering.

HI Brian,-- Maybe a fresh air leak somewhere.-- Maybe renter takes long hot showers in the tiny unit.-- Maybe renter cooks spaghetti for a long time long in the tiny unit.-- Maybe mini-splits are too big and not running enough.-- Maybe mini-splits mounted too low to grab higher humid air (hot air rises).-- Maybe it's an air circulation problem, ask the renter to put a small 9" fan (like a Vornado) on the floor in the doorway (pointed up at a 45% angle) in the bedroom.

I offered asking price of 89k but during due diligence found out it did not have central air. 

@Candace Buckstead  I definitely recommend first house hacking a single fam home, or a duplex triplex or quadplex (since those are all eligible for owner occupant mortgages).I would probably suggest not starting off with an STR (air bnb).