What is air conditioning?

What this means for your home project

1. Read the air conditioner’s nameplate and note the refrigerant type for the service request. Source: U.S. Environmental Protection Agency, read 2026-11-06.
2. Ask the installer to state the home’s cooling load from Manual J and the equipment selection from Manual S. Source: Pacific Northwest National Laboratory, read 2026-11-06.
3. Request a written proposal listing the equipment model numbers, project costs, job schedule and warranty information. Source: ENERGY STAR, read 2026-11-02.
4. Ask the technician to explain how a proposed HCFC-22 refrigerant conversion would affect system performance and energy use. Source: U.S. Environmental Protection Agency, read 2026-11-06.

How does air conditioning work?

A residential split-system air conditioner has indoor and outdoor equipment. PNNL (read 2026-11-06) explains that refrigerant reaches the indoor coil, "where it cools the distribution air." One ton means 12,000 Btu/hour of cooling capacity; an oversized system can shut off before removing enough moisture. (source)

“Refrigerant is piped to the evaporator coil in the air handler unit where it cools the distribution air.” (source) “Residential air conditioners are typically split systems, which refers to the fact that there is an outside unit and an inside unit: the condenser and compressor are part of an outside unit, and the evaporator and expansion valve are located within the air handler in the inside unit (Figure 1).” (source) “One ton equals 12,000 Btu/hour of cooling capacity.” (source) “An oversized system will turn on and bring the air temperature down below the thermostat set point quickly then shut off before the system has had time to remove moisture from the air, which can cause high humidity problems in the home, especially in humid climates.” (source)

What is the difference between an AC and a heat pump?

An air conditioner typically cools and dehumidifies, while a heat pump can also heat. PNNL (read 2026-11-06) explains that a heat pump can run "the refrigeration cycle in reverse to provide heating." In mild to temperate climates, that can replace both cooling equipment and a furnace nearing its expected end of life. (source)

“Because A/C units typically provide only space cooling and dehumidification, the demise of the current A/C system is an opportunity to re-assess the homeowner’s needs.” (source) “In mild to temperate climates, if the home also has a furnace nearing the end of its expected life, an air-source heat pump could replace both pieces of equipment because a heat pump can operate the refrigeration cycle in reverse to provide heating.” (source)

What affects an air conditioning quote?

Existing ductwork affects central air-conditioning installation cost. DOE’s home-cooling guide (read 2026-11-04) flags expense "if you don’t have ductwork already." A split-system installation also connects indoor and outdoor equipment with refrigerant piping and electrical wiring, as PNNL explains; include those connections when describing the installation scope. (source)

“Can be expensive to install if you don’t have ductwork already.” (source) “Split systems have to be plumbed, i.e., the indoor unit must be connected to the outdoor unit via refrigerant piping, and electrical wiring must be connected to both units.” (source)

How should I select an appropriate technician?

An air-conditioning service company should be able to explain its refrigerant-handling credentials. EPA (read 2026-11-06) says to ask whether technicians are "Section 608-certified." EPA also says homeowners can ask to see the technician’s certification card; make that a specific question before arranging refrigerant service. (source)

“When speaking with an AC service company, ask if their technicians are Section 608-certified.” (source) “You can also ask a service technician to show you his/her certification card.” (source)

What effect will retrofitting my system have on energy use?

An air-conditioning refrigerant conversion can affect performance and energy use. EPA (read 2026-11-06) says equipment generally runs most efficiently on "the type of refrigerant it was designed for". Existing HCFC-22 units need not be converted under EPA requirements; alternative refrigerants require component changes. Ask the technician to explain the proposed conversion’s effects. (source)

“Air conditioning equipment generally runs most efficiently on the type of refrigerant it was designed for, but when the time does come to replace or retrofit your system, there are many non-ozone-depleting alternatives available.” (source) “Alternative refrigerants will not work well without making changes to system components.” (source) “There is no EPA requirement to convert existing HCFC-22 units for use with a non-ozone-depleting substitute refrigerant.” (source) “If a homeowner chooses to have their appliance retrofitted to another type of refrigerant it is important to ensure a technician with Section 608 certification recovers any remaining HCFC-22 in the system before adding the non-ozone depleting alternative and explains how the conversion to a different refrigerant might affect the system’s performance and energy use.” (source)

May I purchase my own refrigerant to recharge my appliance?

Recharging an air conditioner requires EPA Section 608 certification. EPA (read 2026-11-06) says refrigerant for stationary appliances is sold only to "certified technicians or the companies that employ them." Treat purchasing refrigerant and recharging the appliance as technician work; owning the air conditioner does not remove that certification requirement. (source)

“Refrigerant for stationary appliances is only sold to certified technicians or the companies that employ them.” (source) “Section 608 Certification is required to recharge appliances.” (source)

How should I dispose of appliances containing refrigerants?

An air conditioner awaiting disposal should remain intact. EPA (read 2026-11-06) cautions against "cutting refrigerant lines or removing compressors." Governments and private organizations may arrange appliance pickup; ask about collection rather than dismantling the refrigerant circuit before the appliance is removed. (source)

“Do not tamper with an appliance before it is disposed of, such as cutting refrigerant lines or removing compressors.” (source) “Many governments and private organizations also can arrange for curbside pickup of appliances.” (source)

Sources

• Air Conditioning — Pacific Northwest National Laboratory; read 2026-11-06.
• Homeowners and Consumers: Frequently Asked Questions — U.S. Environmental Protection Agency; published 2026-04-01; read 2026-11-06.
• HomeCooling101: central-system installation consideration — U.S. Department of Energy; read 2026-11-04.
• 10 Tips for Hiring a Heating and Cooling Contractor — ENERGY STAR; read 2026-11-02.