Several factors can increase the cost of your air conditioner installation. If you need a new thermostat, for example, or if the design of your house is such that substantial amounts of duct work are required to link with your existing furnace, you'll pay more than average.
The seasonal energy efficiency ratio (SEER) is also a critical factor. This ratio is a measure of an A/C unit's total cooling output (measured in BTU) during a season, divided by its total electric energy input. The higher the resulting number, the better. Currently, all units sold are over 13 SEER, and some can perform at up to 27 SEER.
The advantages of improved SEER ratings are lowered energy costs and cooling times, but they come with a corresponding cost increase. If your hot season isn't particularly long, the increased price may not be worth it.
It's also possible to quiet a noisy air conditioner. Louder units can run over 80 decibels on a hot day, which is painful up close. Many municipalities have passed laws that require new installations to be under a certain decibel level. At 75 decibels, for example, you'll probably hear the unit from the garage or through a window on the same side of the house, while at 70 it will begin to fade into background noise. Most popular brands offer high-efficiency, low-noise models for an increased price.
Air conditioning costs depend in large measure on whom you hire, what size system you need and your A/C unit's overall efficiency.
Have you hired an HVAC contractor to install a new A/C system? Tell us about it in the comments section below.
Editor's note: This is an updated version of an article originally posted on June 17, 2013.