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Window AC units use a fair amount of electricity, but significantly less than central AC systems. Because they are more energy-efficient for cooling individual rooms or small spaces, their usage is comparatively low. On average, a window AC unit consumes between 500 and 1,400 watts, while a central AC system uses over 3,500 watts—meaning a window unit uses about one-third of the energy. This typically translates to a monthly running cost of $15 to $40, although this can vary depending on external factors.

When deciding whether to repair or replace your air conditioner, several factors should be considered. It is generally worth repairing the unit if it's less than 10 years old, the warranty is still active, and you're dealing with a one-off issue. Most central AC units last about 15 years, while window units last 8 to 10 years. If your unit is approaching or has surpassed the 10-year mark and requires frequent or costly repairs (e.g., over $5,000), replacement is often the more sensible long-term investment. For older, inefficient, or out-of-warranty units experiencing multiple problems, replacing it is typically the better choice.

The cost to install a ductless mini-split AC system ranges from $2,000 to $14,000, depending on the type of unit, the number of zones or rooms, and the complexity of the installation. On the low end, a system for one or two zones in a single room costs around $2,000. Covering two zones for more rooms can cost between $6,000 and $8,000. For a larger multi-zone system to cover an entire home, costs can be $14,000. If you don’t already have an AC system in place, you may need to add the cost of permits, an electrician, and a concrete pad.

The general rule of thumb for figuring out how much AC tonnage you need in your home is that for every 500 to 600 square feet of space you need to cool, you’ll need one ton of AC cooling power. So, a 1,000-square-foot home will need 2 tons of AC power.