Repair or Replace: When an Old AC Is Not Worth Fixing

Repair or replace AC: four questions that settle it

Answer these in order, using the repair quote and the data plate on the outdoor unit. No single answer decides it. If two or more land in the right-hand column, price a new system before you say yes to the repair.

ENERGY STAR suggests considering a new unit once a heat pump or air conditioner passes 10 years, and it points to frequent repairs, rising bills and uneven rooms as signals. Trade guides tend to put central AC at 12 to 17 years. Those are rough markers, not expiry dates, and plenty of well-kept systems beat them.

A simple way to compare the two numbers

Divide each option by the years it buys you. A repair quote looks small and a new system looks large, until you put them on the same basis.

1. Take the repair quote and divide it by the years you realistically expect from the old system after the repair.
2. Take the replacement quote and divide it by the expected life of a new system.
3. Compare the two annual figures, then add the likely cost of the next failure to the older system's side.

Here is an example with invented round numbers, not a real job or a quote from us:

When the yearly figures are that close, replacement usually takes it, because the old system's next failure is not in the sum. Swap the $1,200 repair for a $250 capacitor, and repair wins by a wide margin. That is the point of doing the math.

For scale, MyHomeScore reports full systems at $4,400 to $11,000 in 2026, and HVAC Project Cost reports AC plus furnace at $8,000 to $17,000. Those are published guides, not our prices, and they vary widely with the house. Your own two quotes are what count.

When is repair the right call?

Repair when the fault is small and the system is otherwise sound.

• The system is under 10 years old and the part is a common one.
• The failed part is electrical: a capacitor, contactor, relay or fan motor.
• The problem is a clogged drain or a loose connection.
• Cooling has been good right up to the day it quit.
• You plan to sell soon, or a whole-house project is a year or two off.

When should you stop fixing it?

Stop when the money is going into a system that is ending its run.

• The compressor has failed on a system past about 15 years.
• The same refrigerant leak has been topped off more than once.
• The coil is leaking and the outdoor cabinet is rusted through at the base.
• You have paid for repairs two summers running.
• The system cannot keep up on the hot days, or the house stays clammy.

Humidity and uneven rooms are worth a look before you buy, though. ENERGY STAR notes that those can come from leaky ducts as much as from equipment, and a new AC will not fix a duct problem.

Should you replace it before it fails?

Often, yes, if the system is past about 15 years and you have the choice. A planned replacement gives you a few things a July breakdown does not.

• Time to compare. You can get two or three quotes, ask for a load calculation and look at efficiency options without a hot house pushing you.
• Better dates. Spring and fall are quieter for most installers, and a mild week means nobody is sweating while the old unit comes out.
• A wider choice of equipment. During a breakdown you tend to get what is in stock. A planned job can wait for the right match.

The trade-off is plain: you may give up a few more summers from a unit that still runs. If it cools well, the bills are steady and no large part has failed, keep using it and set money aside. The goal is to have the decision made before the failure, not to replace a healthy system early.

How much does the refrigerant matter?

It matters most on an R-22 system with a leak. The EPA says you can keep servicing an older unit and that it does not require replacement. But since 2020, only recycled, reclaimed or previously produced R-22 can be used, and that supply is limited. Retrofits are allowed, though the EPA says substitutes generally need component changes to work well. On a system already past 15 years, those costs rarely make sense.

R-410A is being phased down. Home systems made for sale since January 2025 run on A2L refrigerants, chiefly R-454B and R-32. A working R-410A system does not need to go anywhere, so do not let anyone rush you on that alone.

What does a replacement actually change?

Plan on more than a new outdoor unit. Missouri falls in the federal North region, where split-system AC under 45,000 Btu/h has a 13.4 SEER2 floor, so even a base model is a step up from a 2010 system. ENERGY STAR says high-efficiency units can save up to 20 percent on heating and cooling costs when installed correctly.

That last phrase matters. A proper AC replacement starts with a Manual J load calculation, not a copy of the old tonnage. Older houses often got larger units than they needed, and an oversized AC short cycles and leaves the air damp. The Manual S limit of about 15 percent over the cooling load is a good question to raise.

What we tell customers before a big repair

Ask for both numbers at the same visit. You will see our price before work begins, and on an older system it is fair to ask us for a replacement figure next to the repair. You should not have to pay for the repair to find out what the alternative was.

Budget with today's rules in mind. The 25C federal credit stopped with equipment placed in service by December 31, 2025, which leaves 2026 installs with no federal HVAC credit. Check with your tax adviser, and read our notes on Missouri rebates before you sign.

If you are in Washington, we are about 38 minutes from your door, and the town's mix of historic and newer homes means the right answer varies by house. A small fix may be all you need, and our AC repair page covers what those involve.

Have a quote in hand and not sure what to do with it? Call (209) 563-1270 Monday through Friday, 8 to 4, with the system's age and the repair you were told it needs.