Repair or Replace an AC Over 10 Years Old

An air conditioner almost never dies all at once. It starts cycling more often, drawing a little more power, making a new noise, and then one day it throws an error code and stops. In between, there are often two or three years during which you pay for repairs on a unit that will never return to its original performance.

The question "do I repair or replace?" is rarely settled by eye. It is settled with four pieces of information: the installation's actual age, the refrigerant it contains, its measured consumption, and the price of the parts still available. Here is how to gather these four elements and what they tell you, whether for an apartment or a commercial space.

Actual age, not perceived age

Most split air conditioners installed in the Paris region last between twelve and twenty years when they are maintained. Maintained means: coils cleaned, filters monitored, refrigerant charge checked, condensate drained properly. A unit that has never been opened since installation rarely reaches the top of that range.

To establish the actual age, don't rely on memory. Look at:

• the nameplate on the outdoor unit: brand, model, serial number, year or week of manufacture, refrigerant type and charge in kilograms;
• the installation invoice, if it still exists, which gives the commissioning date;
• the physical condition of both units: corrosion of the chassis, coil paint, cracked connection trunking, hardened and crumbling pipe insulation.

That last point matters a great deal in Paris. An outdoor unit in a courtyard, on a loggia or on a roof takes rain, dust and sometimes construction spatter. Two units of the same age can be in very different condition depending on their exposure.

A simple rule of thumb: under eight years, you almost always repair. Between eight and twelve years, it all depends on which part has failed. Beyond fifteen years, repair is only justified if it is minor and the rest of the installation is sound.

Refrigerant: the criterion that most often decides

This is the point many owners discover when the quote arrives. The refrigerant inside your unit determines whether repairing it is even possible.

Residential split systems installed in France up to around 2015-2018 generally contain R-410A. More recent units use R32, whose global warming potential is roughly three times lower. Regulation (EU) 2024/573 on fluorinated greenhouse gases, which came into application in March 2024, continues the gradual reduction of HFC quantities placed on the European market and sets a phase-out timetable for new equipment according to its capacity and GWP.

What this means for you in practice:

• a refrigerant subject to a quota reduction becomes scarcer and more expensive; recharging it after a leak costs more every year;
• recharging alone is prohibited when a leak is known and has not been repaired: the French environmental code requires repair before recharging, and the leak-tightness check must be redone after the work;
• so on a fifteen-year-old R-410A unit with a slow leak, you pay twice: once for leak detection, then for a refrigerant whose price keeps rising, with no guarantee it won't happen again next summer.

The rules on checks, record-keeping and CO2-equivalent tonnage thresholds are detailed in our article on leak-tightness checks and the F-Gas regulation. The one principle to remember here: an old unit that is losing refrigerant is a unit at the end of its economic life, even if it still blows cold.

A leak properly repaired on a sound circuit is a repair. A second leak on the same circuit within three years is a signal to replace.

Measured consumption, not estimated

This is where the gap between a 2010 unit and a 2026 unit becomes visible. You don't measure it by reading an energy label: you measure it on your own installation.

Two readings are enough to put facts on the table.

Current draw. Using a clamp meter, the technician measures the current drawn by the outdoor unit in steady-state operation and compares it with the nameplate rating. A current well above the rated value under normal conditions points to a compressor working too hard: fouled coil, incorrect charge, weak fan, or a tired compressor.

Supply/return air temperature difference. The technician measures the temperature of the air returning at the grille and that of the air being supplied. In cooling mode, on a residential split in good condition, the difference is often between 8 and 12 °C depending on the unit and the conditions. A collapsing temperature difference while current draw stays high means the unit is consuming without producing. How to read these lines in detail is explained in our article on the service report and its measurements.

Between visits, you can track two indicators yourself. A plug-in power meter or a metering module fitted on the air conditioner's circuit gives real consumption in kWh over a season, to compare from one summer to the next. And an indoor thermo-hygrometer placed in the main room shows whether the unit actually reaches its setpoint or runs non-stop without getting there.

A useful order of magnitude: moving from an older-technology split, with no variable speed or with a tired compressor, to a properly sized modern inverter split often cuts consumption by around 25 to 40% for the same comfort. That range depends on the unit, the home's insulation and the settings: it is no substitute for readings taken at your place, but it gives you the ballpark.

The price of parts: the three families of faults

Not all faults carry the same weight in the decision. It helps to sort them.

Minor faults: repair, no hesitation

Start capacitor, fan board, temperature sensor, remote control, condensate lift pump, louvre motor, display board. These parts are generally available and the cost stays moderate compared with a full replacement. On a ten-year-old unit that is clean and leak-free, repair is the right call.