@Nova MendozaI would recommend Tom Corcoran at Edge Heating and Air. 

When we originally entered this home my GF walked through the kitchen, with walls covered in spattered food (he heated cans of food on the stove) & threw up in the back yard.

My land tripled and I did the build out and plumbing and heating.

I don't have enough equity in the home to fix the central heat and air and did window units instead.

That property didnt require any work but I did remodel 1 bathroom and added forced air heating. 

Maybe new heat, new hot water tanks.  

Tucson is wonderful (except the heat) but there are a lot of areas of town with serious drug/ gang / theft problems, and the rents usually reflect that!

In my last duplex, when the larger unit's heat pump and blower went to crap, I replaced both the blower and outside unit for under $5000 (and with great equipment).That said, it may not hurt you to spend the $600 or whatever it is for the home warranty YoY, if you want a little extra peace of mind and can afford it, since you're fairly sure things are going to need replacement soon.

They'll give you the charges for the last year.The listing mentions that the owner pays "common area gas heat," but you don't have an expense for that.What about management?

Roughly 1300 sq ft of living and rest was a heated shop.