If you are interested in replacing your air conditioner, and are trying to do most of it yourself, I will do everything I can to help get you started!
An important first step is sizing the space/slot where the air conditioner will go (and air conditioner sizing). This first depends on whether you are interested in a window, wall, or a central air conditioner. If it’s a window air conditioner you’re interested in, you have to measure the window space, when the window is both open and closed (don’t count on a closed window to support the weight of the air conditioner). If it’s a wall air conditioner, seriously consider whether cutting a hole in the wall is a viable option. Sometimes choosing a wall air conditioner that looks good without having to be stuck inside a wall, is the better alternative to a messy and costly remodeling job, altercations with a landlord, as well as money off your deposit. If it’s a central air conditioner you want, and you live in a house, it’s important to size both the condenser that will go on the roof or the ground outside the house, the ducts and the space they will go in, as well as the vents that will blow the air into the rooms you want cooled.
Doing this before calling a professional will help make you sound more informed (and harder to swindle), and will also help you narrow down specific options and prices (while talking to a professional or doing your own research online). All of these things will save you time and money, before you even decide to commit to a specific window, wall, or central air conditioner and/or heater!