Question: I am very much a newbie when it comes to this stuff. I have to replace a broken light switch. When I took it apart, this is what the wiring looked like- one wire backwired and one using the side screw. What does this mean? Can i rewire it the same way with a new switch? Thank you in advance. [![enter image description here](https://i.stack.imgur.com/xMppD.jpg)](https://i.stack.imgur.com/xMppD.jpg)

Answer: 
First, if it works *even at all*, check with your power company about any appliance upgrade assistance they may have. They will often subsidize replacement with efficient appliances, *especially air conditioners*, because every watt of *A/C* draw they eliminate is a *peaking unit* power plant they don't have to build. Peaking units are by far the most expensive because the bank wants the mortgage paid exactly the same as a baseload 24x7 nuke, but the peaking unit only makes hay a few hundred hours a year. 

There's window units, *and then, there's wall units*.
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Wall units are much tougher and more industrial units than window air conditioners. They also have a much tougher and more industrial price :) 

As such, people like to substitute for window units, which is not a good idea. Window A/Cs assume a threshold only a few inches wide, especially on the top. The wall passage tends to be deep, and the window unit won't perform well there. 

One could install a window :)
Yes you can replace the unit make sure the vents are in similar places you don’t want the sleeve blocking outside air flow normally on the sides and back. Also make sure the unit tilts slightly to the outside so the water can drain outside.