Replacing an air conditioner is a big decision. A properly sized, efficient system can keep the home comfortable for years and lower energy bills. Choosing the right type and size, and having it installed correctly, matters more than the brand.
Sifixit is a free referral service. Call the number on this page and you will be connected with an independent heating and cooling provider where one serves your area. Calling costs nothing and you are never obliged to hire anyone.
Signs it may be time to replace your AC
Several of these together usually point to replacement.
- The system is more than 10 to 15 years old
- Repairs are frequent or expensive
- It uses R22 refrigerant, which is no longer produced
- Some rooms never get cool
- Energy bills keep rising
- The compressor has failed on an older system
What to do right now
If your AC fails during extreme heat, keep vulnerable people cool while you get quotes, and ask about temporary cooling if replacement will take days.
- Find the age and model on the outdoor unit label
- Gather a year of energy bills
- Note which rooms are hot or cold
- Get at least two written quotes
- Ask each installer about sizing
Choosing a new system
Central air conditioner
Cools through existing ducts, usually paired with a furnace.
Heat pump
Heats and cools efficiently with electricity, and can replace both an AC and a furnace.
Matched systems
Replacing the AC and furnace together so they are sized to work well with each other.
Efficiency
Higher SEER2 ratings cost more upfront but use less energy.
How AC replacement works
- The installer calculates the right size, ideally with a load calculation such as Manual J.
- Ducts are checked for leaks and size problems.
- The old system is removed and refrigerant recovered.
- The new system is installed, with a permit where required.
- The system is charged, tested and set up with the thermostat.
Things to agree before work starts
- The exact model, size and efficiency rating
- Whether ducts or the thermostat are included
- Permits, inspections and haul away
- Warranty on equipment and labor, and any registration needed
Questions to ask before you hire
- How did you decide on the size?
- Will you check my ducts?
- What refrigerant does the new system use?
- Are permits and haul away included?
- What warranties come with the system and your labor?
Frequently asked questions
How long does AC replacement take?
Many straightforward replacements take a day. Duct work or switching system types takes longer.
Is a bigger AC better?
No. An oversized AC cycles on and off, wastes energy and removes less humidity. Proper sizing matters.
Should I replace my furnace at the same time?
If both are old, replacing together can make sense and ensures they match. A heat pump can replace both.
How do I know what size AC I need?
A load calculation, such as Manual J, based on your home’s size, insulation, windows and climate decides the right size, not the size of the old unit.
Learn more
Our main heating and cooling guide covers the wider picture, including what affects the cost and when to call a professional.
Looking for ac replacement? Call the number on this page to be connected with an independent local provider. For more background, see ENERGY STAR’s heating and cooling advice.
This site is a free service to assist homeowners in connecting with local service contractors. All contractors are independent and this site does not warrant or guarantee any work performed. It is the responsibility of the homeowner to verify that the hired contractor furnishes the necessary license and insurance required for the work being performed. All persons depicted in a photo or video are actors or models and not contractors listed on this site.
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