If you consider these things problems , you wait till a sewer backs up , a roof leaks and the furnace needs replacing .  1 key     $ 2.00leaks ,   not specific enoughLocks jamming closed        wd - 40     $ 3.00cracks in walls ,   spackle and paint    $ 100..00mildew    a little bleach and water           $  6.00

House is newer , so you if you have pvc traps , pour 1/2 cup of bleach in every sink to loosen up any crap in the traps .

I would like to just go in with bleach myself and scrub it and kill it but wife says these tenants will expect a pro to come in and is concerned about me disturbing it and getting in the air.4.

I’ve also standardized on white sheets/towels that are washed with Carbona Super White to keep them fresh across stays versus standard bleach that can be disastrous depending on application.

Cleaning the place with bleach water, getting rid of the nasty carpet, and priming the walls made a HUGE difference!

Mold in the laundry area might just be a surface mold problem which can be cured with a disposable breathing mask, some towels, and some bleach spray. 

Split up the money into four parts. 1. layered CD's you won't lose but little gain like 1.5-2% 2. buy 10 individual stocks of products that you understand and believe can grow in the coming economy- tiny houses, ADU's, bleach, beer can production, tents, cheap motor homes, grocery chains, you know the stuff... avoid retail, big box, restaurant chains, travel 3. use for down payment to buy AFTER Halloween another rental in different market - college town is good idea. 4. pay down with the remainder

After that, get bleach wipes, or rubbing alcohol and paper towels, wear clean disposable gloves if you have them. 

Look at the unit, spray the inside with a mild bleach solution and do a hot wash or two with bleach. 

Test fan, for the future, replace if bad. if it’s mild surface mold google best treatment, I think the preferred method switched away from bleach.