I will say the majority of the time HVAC does not produce significant ROI unless you already have a forced air system and you can tie the AC portion into the existing duct work. 

Off-market legal 3 unit in the Bridgeport neighborhood of Chicago, comprising of a brick 2 flat with (2) 3 bed 1 bath units, and rear frame coach house with 3 bed 2 bath.Each unit needed all new plumbing, electrical, duct work and HVAC, 4 new bathrooms, 1 new kitchen, paint, finishes, flooring, etc.

Out here in Phoenix/Scottsdale you're only putting a mini split into an addition that you can't run duct work to, a detached shed/guest house, or a garage.

I also have some minor ductwork that needs to be done.Any contractors you can recommend are appreciated.  

I would guess he does both for <$5k if you already have ductwork ran.Luis-773-575-3423(Let him know you know me!)

The previous owner had added central air for the upper floor, installed in the attic with all ductwork in the attic and defusers in the cieling of the upper floor. 

If needed add a minimum of 15kModerate RehabCan save at least two of the following- Electric, Drywall, Flooring, Plumbing (likely touch ups in the other two)Redo KitchenRedo Existing BathroomsNo framing or architect plans neededPaintFinish BasementAdd a split unit to existing duct work (prevent from tearing up existing plaster/drywall)*Think of a grandma home that does not have knob and tube and has been on top of roof/windows so we aren’t as worried about mold/water damage*Light RehabComps do not need a finished basement or basement is finished to comp standardComps do not need HVAC or you can just add split unit to existing ductworkKitchenBathroomFloorsPaintNo major rehaul of mechanics needed (aka do not need to rip out walls)LipstickPaint, Floors, appliances in the most basic sense ARV Range Full Gut Moderate Light Lipstick +450 (A+) 150-300 N/A N/A N/A 380-450 (A) 90-120 70-75 N/A N/A 270-400 (B/B+) 85-100 60-70 N/A N/A 210-270 (B-) 75-80 60-65 45-55 N/A 170-210(C/C+) 65-75 50-60 40-50 15-30 140-170(C-) 60-70 50-60 35-45 10-20 120-140 (D) 55-65 40-50 25-35 5-15 Philly Neighborhoods Breakdown:A+ : Obvious Prime Real Estate.

44 - What type of ductwork, and what total length?

@David RobertSevere nicotine damage can require extensive cleaning, sealing, and even replacing drywall or HVAC ductwork.

Their a/c starting leaking and has missing ductwork, and is blowing air in random places.