My checklist says, tenant wishes to use "fill in blank" left by previous tenant.BTW, nobody works on window air conditioners, when you can buy a new one at Best Buy for $99 

Thanks Robert, In terms of through the wall, I meant an old fashioned Friedrich -- just a regular air conditioner designed to vent out the back.

He said "she looked like she was loaded" and being a veteran of the Korean war, he wasn't phased much by it.A few years ago another tenant's estranged adult daughter (not living there), broke into her mother's apartment by pushing the window air conditioner into the bedroom and crawling through the window.

I have a 40 year old air conditioner unit working great and one that is 10 years old that is having problems already.

If there's no ducts installed they have mini split/ductless air conditioners.

Also, the model unit had built-in air conditioner but his unit had big stupid air conditioner. so everything was different than the model unit.and today he said that there was a homeless sleeping at the hallway on his floorso they refused to show him the unit that he already made contract and no one is living, but the unit condition was terrible unlike model unit. is this legal?

We put a little pump unit in the showers with soap, shampoo, conditioner and then buy those by the gallon.

With a ductless heat pump, you automatically have an extremely efficient air conditioner as well.

When I needed a new air conditioner - oops.

So your turning units, like you might with apartments, fixing bad roofs, water heaters, heaters, air conditioners, leaking faucets, toilets, bad flooring, broken windows etc...