This causes moisture in walls, even cabinets feel moist (cabinets have warped). 

Gently talk to him that this is a business and you need the income. 

$15.00 per closetLight fixtures – glass cleaned and bulbs replaced $15.00 per fixture /$1.00 per bulbCeiling fan, blades- clean top & bottom, motor housing dust free $30.00 -$50.00Vacuum – per room (carpet is shampooed by management after move out at no charge) $15.00Carpet- burns, stains, soil as per estimate / replacementBaseboards – dust, wipe off, vacuum per room $15.00 per roomA/C vent cover – vacuum, dust $15.00Windows – Glass, tracks, clean and dust free $20.00 per windowTo remove window pane, slide pane to center of track- grasp each side, gently lift up and pull forward to remove, clean, replace in correct order.Window- Glass replacement $35.00 per windowScreens replacement- $25.00 per window -$40.00 per patio door $25.00- $40.00Mini-blinds replacement $20.00 per windowPatio door – Glass, clean both sides, track vacuumed, wiped clean $35.00Patio blind replacement $50.00 per windowOutdoor patio globe- clean $15.00Sweep off patio and railings $15.00Bathroom exhausts fan/vent cover, clean, dust free $15.00Bathtub, clean tub and tile surround $25.00 – $60.00Bath sink, vanity/countertop, clean $20.00Bath – medicine cabinet, clean inside, mirrors, light guard $20.00 minBathroom floor & wall tile – wash, clean tile $20.00 minTowel bar replacement $18.00 minToilet tissue spindle replacement $5.00Toilet – clean inside bowl and outside $20.00 minToilet seat replacement $20.00Kitchen cabinets – wipe off grease; remove shelf paper, empty out $20.00 minKitchen-sink, countertop, wipe off, clean garbage disposal ring $20.00 minDishwasher – clean, remove any food particles from inside $20.00 min Vent hood – wipe off grease, clean filter, clean light guard, top/underside $20.00 minStove/ Oven- wipe off exterior, clean under drip pans, clean oven/racks $25.00 min to $125.00Drip pans – clean (replacement cost is $7.50 each) $30.00 maxBroiler pan replacement $20.00Refrigerator/ Freezer-wash off exterior, top, seals, inside, crispers $20.00 min to $75.00Walls / Woodwork – remove nails, screws $15.00 minWallpaper boarders-removal per room $50.00 minNicotine – stained walls/ woodwork that require cleaning (see below explanation) $25.00 per hour min.The cost to prep the unit for painting requires the walls and woodwork to be washed clean from the smoke odor/ and nicotine stained damage.GaragesGarages should be swept clean and all debris removed.

This is my first post so please be gentle :)

Besides flashlight, measuring tape, telescoping ladder,outlet tester, and electronic thermometer\ moisture detector what else should I pack.

We bought gentle fixers, moved into them and improved them over time.  

But I agree with Dawn, the best idea is to call a moisture specialist.

But most pools are in basements and now you've got chlorine and moisture issues you have to deal with or it could affect the rest of your cabin.Hot tubs are an absolute must.

(The "Contract to Buy and Sell, Residential" is the typical offer used by us.)That said, I would gently push back on your premise. 

If their is high moisture content in the basement (and I assume the HVAC unit is IN the basement), this could certainly be a contributing factor, and may not be an inexpensive repair.