Quick Answer
The repair-or-replace decision comes down to four findings, and the system's age is only a prompt to check them. A failed compressor or a leaking evaporator coil carries a repair cost high enough to reconsider the whole system. Repeat failures across one season point at a system near the end. A single fault on an otherwise sound unit points at a repair. The $5,000 rule gives a rough gate, and measured condition gives the answer. Diagnosis names which situation is yours, in writing, before any money gets spent.
The Answer
Age Is A Prompt, Not The Answer.
A system's age tells you when to look closely, not what to do. Central air in Greater Boston commonly lasts 12 to 17 years. A unit inside that range with one failed part is often worth repairing. The same age with a failing compressor tells a different story. Condition decides the call, and condition comes from readings rather than the date on the cabinet.
“The cabinet's age opens the question. The readings close it.”
Second opinion calls where our diagnosis supports repair
Second opinion calls where replacement is the right call
Common central AC service life in Greater Boston
The Two Repairs That Change The Math.
A failed compressor and a leaking evaporator coil are the two costs that tip a decision toward replacement. Both are expensive, both sit at the heart of the system, and both often arrive on units already past ten years. A capacitor, a contactor, or a fan motor rarely reaches that threshold. The part that failed matters as much as the bill attached to it.
One Fault Or A Pattern.
A single component failure and a pattern of failures lead to different decisions. One bad part on a system that has otherwise run clean is a repair. A second and third unrelated failure inside one season signals a unit wearing out across the board. Refrigerant added every summer is a pattern too, since a recurring leak means money spent renting time rather than fixing the cause.
“Two unrelated failures in one season say more than any single repair bill.”
What The $5,000 Rule Misses.
The $5,000 rule multiplies the system's age by the repair cost, and replaces the system when the total passes $5,000. It offers a quick gate and nothing more. The rule cannot see a heat exchanger crack, a corroded coil, or a compressor drawing high amperage, and it treats a capacitor and a compressor as the same kind of problem. A measured diagnosis reads what the rule cannot, which is why the number is a starting point rather than a verdict.
The 617 Philosophy
Replacement gets recommended more often than the evidence supports. Homeowners reach us after another company has already quoted a new system. Our diagnosis supports repairing the existing unit about 80 percent of the time. Replacement is the right answer in roughly one home out of five, and we say so plainly when the readings point there. Our technicians earn their pay for diagnosing and repairing systems, never on commission. The recommendation rests on what the instruments show, and the price lands in writing before any work starts.
Frequently Asked Questions
Technical clarification on system performance and diagnostics.
What is the $5,000 rule for AC?
The rule multiplies the unit's age in years by the repair cost. A result above $5,000 suggests replacement, and a result below it suggests repair. The number works as a rough gate. It cannot read compressor health, coil corrosion, or refrigerant condition, so a measured diagnosis stays the reliable guide.
Is it worth repairing a 15 year old AC?
Sometimes, and the fault decides it. A 15 year old system with a failed capacitor or fan motor is usually worth the repair. The same system with a failing compressor or a leaking coil moves toward replacement. Readings on the specific unit answer the question better than the age.
My AC needs refrigerant every summer. Repair or replace?
Neither, until the leak gets found. Adding refrigerant each year treats the symptom and leaves the cause in place. Leak detection locates the hole once, and the repair holds. A Cambridge homeowner spent about $8,750 over five years on top-offs before a single leak repair solved it.
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