Tell them if they don't like it they can move and should because they're going to end up blowing your compressor. 

Because when the roof needs replacing or her compressor on her condenser goes out you can’t call her and ask for 2k she will be likeYou’re the landlord!!

gas furnace costs about $900. compressor ac system cost is more brand dependent.That is just materials.

Capacitor failed, which shut down the cooling fan which in turn overheated the compressor.

That's an old R22 compressor and I wouldn't waste time or money trying to refurbish it.

Clearly the OP has put himself in a good position to buy and knows it may be missing appliances and maybe missing an outside compressor.

On the two-dial kind, the "freezer" one sets how long the compressor runs (it's the thermostat), and the "fresh-food" one sets how much cold air from the freezer is allowed to leak into the fresh-food compartment (it controls a flap in the ducting). 

The properties were in nice neighborhoods and before I closes escrow on 3 properties the air conditioners compressors were stolen and probably sold for the copper and aluminum inside them.

Pipelines and Compressor stations have slowed down since most have been built already.

It will have 240 V AC wires from the house on one side, and 240 V AC wires to the compressor and fan motor on the other.