Repair or replace? The honest maths

The rule, and why it is only a starting point

Multiply the age of the system by the repair cost. If the result is over about 5,000, replacement usually wins. A 15-year-old unit needing a $400 repair scores 6,000, so it is borderline. A 6-year-old unit needing the same repair scores 2,400, so you repair it without thinking twice.

That is a useful sanity check, not an answer. It ignores the two things that actually decide most cases.

What actually decides it: refrigerant and the compressor

If your system uses R-22, the calculation changes completely. R-22 has not been produced since 2020, and what remains is reclaimed and expensive. A refrigerant-related repair on an R-22 system can cost more than a meaningful chunk of a new unit, and it will happen again.

If the compressor has failed, you are usually looking at $1,800 to $3,400 on a component that is the heart of the system. On anything past 10 years, that money is better spent on a new system with a full warranty rather than a rebuilt heart in an ageing body.

Reasons to repair that people underrate

• The failed part is cheap. A $250 capacitor on a 17-year-old unit is worth fitting. It may buy two more seasons, and two more seasons of savings buys a better replacement later.
• You are selling within two years. A working system passes inspection. A new one rarely returns its cost in sale price.
• It is August and you have not researched anything. A repair now, a considered replacement in October, is almost always cheaper than a panic replacement in a heatwave.
• The system was correctly sized and has been maintained. Those two things predict remaining life better than age alone.

Reasons to replace that people underrate

• You are on your third repair in two years. The pattern matters more than any single quote.
• Some rooms have never been comfortable. Replacement is the moment to fix sizing and ductwork, and doing it separately later costs much more.
• Your bills have climbed steadily with no change in habits. That is efficiency loss, and it is money you are already spending.
• The system is oversized. This is extremely common in Charlotte, and it is why some houses feel cold and clammy rather than comfortable. Only replacement fixes it.

How to tell if you are being pushed

Ask what specifically failed, and ask to see it. A technician who has genuinely diagnosed a fault can show you the part and explain it in plain words. One who cannot, or who moves quickly to a replacement brochure, has not earned the recommendation.

Ask whether the technician is paid commission on system sales. It is a fair question and the answer tells you a great deal. Ours are salaried, which is exactly why we can afford to fit the $340 capacitor and tell you it will probably hold for two more summers.

Then get a second opinion in writing. We give those free, including on other companies' quotes, and a fair number of them end with us telling people their system is fine.