Overview
Installing central air conditioning, or replacing a system that has reached the end of its life, is one of the larger home equipment decisions most people make. A split system has an outdoor condenser and an indoor evaporator coil, usually sitting on top of a furnace or air handler, connected by refrigerant lines. The equipment itself matters, but the quality of the installation, including sizing, refrigerant charge, airflow and duct condition, has a large effect on comfort, efficiency and lifespan.
Homes without existing ductwork have other options. Ductless mini-split systems place one or more indoor heads in rooms and connect to an outdoor unit. Some homes add ducts in attics or basements. And in many climates, heat pumps, which provide both cooling and heating, are now considered alongside traditional air conditioners whenever cooling equipment is replaced.
A thorough contractor will visit the home before quoting. Expect questions about rooms that are hard to cool, how long you plan to stay in the house, noise concerns and your budget. You should also expect them to look at the electrical panel, the location for the outdoor unit and the condition of the ducts and indoor equipment.
The usual process
- Line set and electrical. Refrigerant lines may be reused or replaced, and a dedicated circuit and disconnect are typically required.
- Walkthrough. A good installer explains filter changes, thermostat settings and warranty registration.
- Load calculation. Sizing should come from a calculation of the home's heat gain rather than a rule of thumb.
- Permits and inspection where required.
- Refrigerant charge and commissioning. After installation, the system should be evacuated, charged and tested for proper operation.
- Equipment matching. The outdoor unit, indoor coil and furnace or air handler should be compatible to achieve rated efficiency.
- Pad and placement. The outdoor unit needs a stable, level base and adequate clearance for airflow and service.
What affects the outcome
- A heat pump may be worth comparing, since it can provide both cooling and heating with one outdoor unit.
- Efficiency is rated in SEER2. Higher-rated units use less energy but cost more; the payback depends on how much you use cooling.
- Warranty registration often has a deadline. Ask who handles it and keep the paperwork.
- Matching with an older furnace may limit options. Some high-efficiency systems require a variable-speed blower.
- Get comparable quotes. Make sure bids specify the same equipment tier, scope and included items.
- Duct condition affects results. Leaky or undersized ducts can undermine even a well-chosen system.
- Oversizing is a common problem. An oversized system can cool quickly but cycle often, leaving humidity and uneven temperatures.
What to have ready
- If you smell gas or suspect carbon monoxide, leave the home and contact your gas utility or emergency services first, before sending any inquiry.
- Describe the symptom in plain terms: no heat, weak airflow, short cycling, odd smells, noises or a thermostat that will not respond.
- Note any rooms that are consistently too hot or too cold, which can point to duct or zoning issues.
- List times you can be reached and when someone can provide access.
- Share the approximate square footage of the home and how many levels it has, especially for replacement quotes.
Signs to slow down
- Pressure to buy immediately with a deal that expires the same day.
- Claims that equipment is dangerous without explaining the specific problem or showing you what was found.
- Quotes that leave out duct, electrical or venting changes that the new equipment will clearly need.
- Reluctance to show license or insurance information.
- Large cash-only payments requested up front.
Questions to ask a provider
- Will you perform a load calculation, and can I see the result?
- Are there current rebates or incentives that apply?
- What warranties cover the equipment and the labor, and who registers them?
- Is a heat pump worth considering for my home?
- Does the quote include permits, electrical work, the pad and removal of the old unit?
- What equipment do you recommend, and what are the alternatives at different price points?
- Will you replace the line set and indoor coil, or reuse them?
- How will you verify the refrigerant charge and airflow after installation?
People also ask
- Are ductless mini-splits a good option?
- They are a common choice for homes without ducts, additions or specific rooms. Comfort and cost depend on the number of zones and the home's layout.
- Should I replace my furnace at the same time as my AC?
- Not always, but replacing them together can make matching easier. If the furnace is older, a contractor can explain the trade-offs of each approach.
- What size air conditioner do I need?
- The right size depends on your home's insulation, windows, orientation, air leakage and layout. A load calculation is the reliable way to determine it.
Related topics
- AC Tune-Ups and Maintenance: What an air conditioning tune-up includes, why maintenance matters, and questions to ask about service plans.
- Thermostats and Controls: Smart and programmable thermostats, zoning and controls, and what to ask an HVAC pro before upgrading.
- Furnace Repair and Replacement: What a furnace repair visit involves, signs a furnace may need replacing, and what to ask an HVAC contractor before you decide.