Check the dates on the water heater, furnace, and air conditioner.

., shampoo, conditioner, soaps, light bulbs, towels, etc.)Here's a calculator that you can use to calculate how much you're actually making from each property. 

+ 1@Tomny Gunter and @Katrina Phttp://www.raleighheatingandairservice.com/what-causes-an-air-conditioner-leak/

I looked at a duplex recently that had one meter and the utilites were paid by the landlord, and there were 5 window air conditioners running with the doors and windows wide open.

I don't believe I have to worry about the deposit as her kids (who were removed) crayoned all the walls so a full paint job is needed, they also ran and indoor air conditioner and it leaked and ruined the hardwood floor and ceiling below her apartment.

If it's the former, I would do the repair as, in my opinion, windows that have ratty or missing screens make the whole house look terrible and it's an issue if the tenants want to open a window to catch a cool breeze rather than run the air conditioner (behavior which should be encouraged, in my opinion).I think the larger question is why, when there are so many properties in the country that cash flow really well, why you're hanging on to one that does not.  

we need to keep our prices were they are for appraisal and comp purposes but I will usually throw in the air conditioner.. those are optional in our market .. cost me about 2200 .. so on a 450k sale that's ok.. but some of the agents got real aggressive for their clients and I hit back with Hey you want all that

You have several options, however I'd like to ask whose air conditioner is it? 

Air Conditioner ?

Also, whenever I have a pest problem, I hire pest control companies under contract for a while, and hire licensed contractor to install window air conditioners, etc. areas where tenants can sue you if not handled properly, such as an AC falling from a third floor window.