One client I worked with found a nice house and her "contractor" said she needed a new electric panel and a new air-conditioner and quoted her prices about double what I pay. 

There are a lot of ways to manage out-of-market/state properties; the PM model may not be the most efficient.in many areas air conditioners are stolen at frightening regularity..  

For most of the homes the carpets alone were $3200 to $4900 plus two coats of paint on every wall and ceiling, replacing broken bathroom sinks, kitchen sinks, faucets, repairing air conditioners, replacing cracked times on roof 36 feet high, bringing in 4 to 8 tons of rocks to make the yards look nice, trimming trees, repairing sprinkler systems and the piping, replacing refrigerators, stoves, washing machines clothes dryers, water heaters, painting garage floors ceilings and walls, bringing in 20-yard trash bins to remove all the carpets, trees trimmings and trash left by tenants, replacing all the window blinds, door knobs that are broken and locks for the main door and locks for the garage door so the keys match, repairing garage door openers that are broke, repairing the garage door rollers and seals, painting the trim outside the house, replacing facia boards that are 36 feet high, replacing window screens and the screens on sliding doors, replacing entire windows just because tenants broke the window locks and they cannot be repaired, replacing kitchen counter tops that are destroyed, replacing all the kitchen doors and drawers because tenants destroyer the cabinets by hanging their wet laundry in the kitchen cabinet doors to dry. replacing garbage disposers, dishwashers and the list goes on and on.

Can't Tenants afford their own $100 window air conditioner?

Example: tenant calls me yesterday to tell me air conditioner stopped working.

Between tenants you will have a much higher risk of your property being broken into, having your air conditioner stolen, having a door kicked in to steal appliances etc. 7.

You'll be surprised how many appliances 2 to 3 years old are for sale I get my best deals in New York City when people leave their high-end apartments they tend to leave air conditioners in the windows the Super's get them and they have storage rooms filled with appliances that's where I get my best deals.

Once we got new water heater, new furnace, new air conditioner, and were ready to rent, we (the property manager and I) realized that the copper wire had been vandalized as well.  

When they moved out, they took window air conditioners that they paid for, but I cut them a break on rent for them to buy.

I'd look into the possibility of installing heat pumps with electric heating elements for very cold days(one per unit, hopefully, in the units which currently have electric heat) these can be installed in the window much like typical air conditioners and they will function as air conditioners in the summer- some can be installed through the wall.