What is an air conditioner?

What this means for your home project

1. Read the air conditioner nameplate and note its listed refrigerant for a service discussion. Source: U.S. Environmental Protection Agency, read 2026-10-31.
2. Request a written Manual S equipment selection tied to the load calculation; ask which capacity the calculation supports. Source: U.S. Department of Energy, read 2026-11-03.
3. Request duct sizing and design in the written scope, identifying the Manual D design to be supplied. Source: U.S. Department of Energy, read 2026-11-03.
4. Inspect the central air conditioner filter monthly and note whether cleaning or replacement is needed. Source: ENERGY STAR, read 2026-11-05.

What are the two types of AC systems?

Air conditioners come in room and central forms. Natural Resources Canada (read 2026-11-06) identifies “room air conditioners and central air conditioners.” A room unit generally serves one room; a split central system has separate indoor and outdoor sections, with the indoor coil mounted in the ducting. (source)

“As mentioned previously, there are two basic types of air conditioners — room air conditioners and central air conditioners.” (source) “A room air conditioner is essentially a smaller version of a central air conditioner and is intended to cool only a small area, usually one room.” (source) “A split-system unit consists of indoor and outdoor sections.” (source) “The indoor heat exchanger, or coil, mounts above the furnace, inside the ducting.” (source)

How does a room air conditioner work?

A room air conditioner moves heat outdoors rather than merely circulating room air. Natural Resources Canada (read 2026-11-06) explains that the unit “removes heat from the living space”. Refrigerant absorbs, transports and releases heat; a window or through-wall unit contains its components together and needs no ductwork. (source)

“Powered by electricity, it removes heat from the living space to maintain comfort conditions during hot, humid weather and conveys it to the outdoors.” (source) “The refrigerant is a substance that circulates through the air conditioner, alternately absorbing, transporting and releasing heat.” (source) “Unlike a central air conditioner, no ductwork is required, and all components are built into a single package that is mounted in a window opening or through the wall (Figure 3).” (source)

What size air conditioner do I need?

Air conditioner sizing should follow calculated heating and cooling loads. DOE (read 2026-11-03) explains that “Manual S provides guidance for equipment selection based on load calculations.” Manual J estimates residential heat loss and heat gain; ENERGY STAR also names ACCA Manuals J and S and Standard 5 for design and installation. (source)

“Manual J outlines the procedures necessary to estimate the heat loss and heat gain of residential structures.” (source) “Manual S provides guidance for equipment selection based on load calculations.” (source) “Ask your HVAC contractor about high efficiency system options and ensure they use the latest design and installation standards (ACCA Manuals J & S, and Standard 5).” (source) “A ton is a measure of cooling capacity.” Source: Natural Resources Canada, read 2026-11-06. “It is equivalent to 3.5 kW or 12 000 Btu/h.” Source: Natural Resources Canada, read 2026-11-06.

Air conditioner vs heat pump: what is the difference?

A central air conditioner supplies cooling, while a heat pump also provides winter heating. Natural Resources Canada (read 2026-11-06) describes central air conditioners as “cooling-only products”. When considering replacement, the distinction is whether the new equipment will handle cooling alone or heating as well. (source)

“Central air conditioners are cooling-only products, whereas heat pumps provide winter heating as well.” (source)

How long does an air conditioner last?

A central air conditioner’s life expectancy is “15 years or longer”, according to Natural Resources Canada (read 2026-11-06)’s guide. That figure describes an expectation rather than an individual unit’s remaining life. The guide identifies repeated problems and major-component replacement, including the compressor, as reasons to consider replacement. (source)

“The life expectancy of a central air conditioner is 15 years or longer.” (source) “When the air conditioner starts giving more problems than seem cost-effective to fix €“ particularly when major components, such as a compressor, require replacement €“ it may be time to replace the central air conditioner.” (source)

How do I clean an air conditioner filter?

Central air conditioner filter care depends on the filter type. ENERGY STAR (read 2026-11-05) says to “check your air filter once a month”. A dirty reusable filter should be cleaned; a dirty disposable filter should be replaced. Natural Resources Canada also directs owners to follow the furnace manufacturer’s instructions. (source)

“Therefore, it’s important to check your air filter once a month in your central air conditioner, furnace, and/or heat pump.” (source) “If it’s dirty either clean it if your system has a reusable filter or change it if your system requires a replacement.” (source) “Furnace filters should be inspected and cleaned or replaced, depending on the type of furnace and the furnace manufacturer's instructions.” (source)

What affects air conditioner cost per month?

Central air conditioner operating costs vary with use, efficiency, insulation, glazing and open doors or windows. Natural Resources Canada (read 2026-11-06) also names “the local climate and electricity costs.” Indoor activities and appliances add cooling load. These are operating-cost factors, rather than a monthly price estimate for a particular home. (source)

“The operating cost of a central air conditioner is influenced by a number of factors, such as how much you use your air conditioner and how efficient it is, the amount of insulation and glazing in your home, and the frequency and duration of door and window openings when the system is operating.” (source) “It also depends on the activities in your home and the use of other equipment and appliances that increase the load on the air conditioner.” (source) “Finally, it depends on the local climate and electricity costs.” (source)

Sources

• Air Conditioning Your Home — Natural Resources Canada; published 2025-01-07; read 2026-11-06.
• Air Conditioning Your Home: types, lifespan and operating factors — Natural Resources Canada; published 2025-01-07; read 2026-11-06.
• A Homeowner’s Guide to HVAC: sizing and design — U.S. Department of Energy; read 2026-11-03.
• Clean Heating and Cooling — ENERGY STAR; read 2026-11-05.
• Homeowners and Consumers: Frequently Asked Questions — U.S. Environmental Protection Agency; read 2026-10-31.