How Long Does an AC Unit Last?

Short answerA central AC unit usually lasts about 10 to 20 years, and sources disagree. NAHB's 2007 study says 10 to 15 years, while Mississippi State University Extension says about 20. ENERGY STAR suggests considering a replacement once a unit is more than 10 years old, especially if it needs frequent repairs or bills are climbing.

What this costs

Our national estimates, not quotes.
Option	Job	Low	High
Replace	AC Replacement	$3,800	$9,050

Why the sources disagree

NAHB's 2007 study lists air conditioners at 10 to 15 years, and unitary systems at 15 and room units at 10 in its appliance table. Mississippi State University Extension says a central system lasts about 20 years. Neither is a promise for one unit, so treat 10 to 20 years as the realistic range.

When age starts to matter

ENERGY STAR uses 10 years as the point to call a contractor and look at options. Warning signs include:

Frequent repairs and rising energy bills
Rooms that are too hot or too cold
Humidity problems or excessive dust
A noisy system

What helps it last

Mississippi State Extension points to dirty coils as the most common cause of poor efficiency and recommends cleaning both coils and having the refrigerant charge checked. ENERGY STAR recommends a contractor check-up each spring and checking the filter monthly. It says airflow problems can reduce efficiency by up to 15 percent.

AC Not Cooling? What to Check Before You Call

Common questions

Should I replace a 10-year-old AC that still works?

Not automatically. ENERGY STAR's checklist looks at age along with repair history and performance. Mississippi State Extension notes that replacing a 10-year-old unit with a more efficient one may save 20 to 40 percent on cooling energy costs, so bills are worth checking.

How long do window AC units last?

NAHB's table lists room air conditioners at about 10 years.