Repair or replace your AC? How the 5,000 rule works

The rule in one line

Age in years × repair estimate = the number you compare with 5,000. Above 5,000, lean toward replacement. Below it, a repair is usually reasonable.

A worked example

Say your air conditioner is 14 years old. Take the repair figure on your written quote and multiply it by 14. If the answer is above 5,000, the rule points toward replacement. Put the same quote against a 7-year-old unit and you get half that number, so fixing it is usually the sensible choice.

Why the rule works as a rough guide

It combines two things that matter: how much life the system has left and how much you’re about to spend on it. A modest repair on a young unit is easy to justify. A large repair on an old one often buys only a year or two before the next failure.

What the rule leaves out

• Refrigerant type. Systems that run on R-22 are expensive to recharge because R-22 is no longer produced in the United States. A refrigerant leak on an R-22 unit usually tips the decision toward replacement.
• Repair history. One failure in ten years is different from a repair every summer.
• Comfort. If some rooms never cool down, a repair won’t fix the underlying sizing or duct problem.
• Efficiency. Newer units use less electricity for the same cooling. How much that matters depends on how many hours your AC runs. In inland Poway, where summers run long and hot, the system works harder than one on the coast.
• Matched equipment. If the furnace is also near the end of its life, replacing both together can make more sense than nursing either along.

Questions to ask before you decide

• How old is the system, and what refrigerant does it use?
• Is this repair likely to be the last one for a while, or is it a sign of more to come?
• If I replace it, what size and efficiency would you recommend, and is that based on a load calculation?
• Will the replacement need a permit and duct testing under Title 24?