How long does an AC unit last?

An air conditioner wears out by running. A unit in Phoenix or Miami runs for most of the year. A unit in a mild climate may run for a few months. Two identical units can reach the end of their lives many years apart for that reason alone.

The one age figure with a clear public source is from ENERGY STAR. It suggests you consider replacement when an AC is more than 10 years old. That is advice about when to start weighing the cost of repairs against a new, more efficient unit. It is not a prediction that the unit will fail.

• Long cooling seasons. More run hours mean more wear on the compressor and fan motors.
• Wrong size. An oversized unit turns on and off more often, and starts are hard on the compressor.
• Dirty filters and coils. Restricted airflow makes the system run hotter and longer.
• Low refrigerant from a leak. Running low on refrigerant stresses the compressor.
• Poor installation. Leaky ducts, a wrong refrigerant charge and bad airflow shorten the life of even good equipment.
• Salt air and corrosion. Coastal air attacks the outdoor coil.

The safe homeowner jobs are simple. Change the filter on schedule. Keep leaves, grass and debris away from the outdoor unit. Keep supply and return vents open and clear. Watch the condensate drain line and pan for clogs and standing water.

Leave the rest to a licensed technician. A yearly tune-up covers the coil cleaning, electrical checks and refrigerant readings that you cannot do yourself.

• Repairs are getting more frequent, and energy bills are climbing. ENERGY STAR lists this combination as a reason to replace.
• Some rooms stay too hot, or the house feels humid even when the AC runs.
• The system has become noisy.
• A major part such as the compressor or a coil has failed after the warranty ended.
• The unit uses R-22 refrigerant, which has not been made or imported in the US since 2020.

When two or three of these show up together, compare a repair quote with a replacement quote. The guide on whether to repair or replace an air conditioner walks through the decision, and the repair or replace calculator scores your situation.

Look for the data plate on the outdoor unit. It is a metal label, usually near the refrigerant line connections. Many plates show a manufacture date. If yours shows only a serial number, the date is often coded into it, and the manufacturer can decode it for you. The plate also lists the refrigerant type, which matters for repair decisions.

The install date can be later than the manufacture date. A home inspection report, a permit record or the original invoice will confirm it.