Short answerA central air conditioner in Southeast Michigan typically lasts 15 to 20 years, with the short cooling season helping it outlast the same unit installed in Florida. The compressor is the component that ends a system's life; capacitors, contactors and fan motors are routine repairs. Pre-2010 R-22 systems and any unit past year 15 with a refrigerant leak are usually better replaced than repaired.
Why Michigan is easier on an air conditioner than most places
A condenser in Ypsilanti runs maybe 600 to 900 hours in a normal summer, concentrated in June through early September. The same unit in Houston runs three times that. Compressor life is mostly a function of run hours and starts, so a system here that gets reasonable care has a real chance at 18 to 20 years, and we see plenty of early-2000s R-410A units and late-1990s R-22 units still cooling in Ann Arbor, Saline and Canton.
What we have that the South does not is the off-season. A condenser sits outside through a Michigan winter with snow piled against it, ice in the fins, and freeze-thaw working on the base pan and the fan motor bearings. Then it gets asked to start cold in May. The electrical components, capacitor and contactor especially, age during those idle months as much as during the run months, and the first humid week of June produces a wave of no-cool calls every year from units that sat all winter and did not start.
The components that fail, in order
- Capacitor. The single most common AC repair, and an inexpensive one. Expect to replace it at least once in the system's life, more on units installed in the mid-2000s with builder-grade parts. Our capacitor guide covers the signs.
- Contactor. The relay that switches power to the compressor and fan. Contacts pit and weld over time. Cheap, quick.
- Condenser fan motor. Bearings wear, especially on units that have been running with a weak capacitor. A mid-range repair, usually worth doing on any system under 15 years.
- Refrigerant leaks. Evaporator coils corrode from the inside, line sets rub through, Schrader cores weep. The repair cost depends heavily on where the leak is and what refrigerant the system uses.
- Compressor. The one that ends things. A compressor failure on a system past 10 years is almost always a replacement, because the part plus labor plus refrigerant approaches the cost of a new matched system, and the rest of the equipment is the same age.
- Evaporator coil. On a system past 12 years, a leaking coil often tips toward replacement for the same reason; you are putting a new coil and a full charge of refrigerant into an old condenser.
What shortens the life
Dirty coils. A condenser coil packed with cottonwood fluff, which falls across Washtenaw County every June, and grass clippings from a mower that discharges toward the unit cannot reject heat. The compressor runs hotter and at higher pressure, and that is what wears it. An evaporator coil fouled by a house that ran without a filter for a few months has the same effect from the other direction.
Low airflow. A clogged filter, a weak blower or an undersized return starves the evaporator, the coil freezes, liquid refrigerant can return to the compressor, and the compressor does not survive many episodes of that. A frozen coil is the warning sign.
Running on a weak capacitor. Every hard start on a drifting capacitor draws locked-rotor amps for longer than it should. Weeks of that can take out a compressor that had years left.
Oversizing. A 4-ton unit on a 1,400-square-foot Westland ranch cools the house in ten minutes and shuts off before it has removed any humidity. The short cycles are hard on the compressor and leave the house clammy. Oversized AC was common in the 1990s installs across the subdivisions in Canton and Pittsfield Township.
Low refrigerant charge that nobody fixed. A system "topped off" every spring instead of leak-repaired runs with low suction pressure and poor oil return, and the compressor pays for it.
What extends it
The systems we see at 20 years had their condenser coil rinsed every year, a clean filter every one to three months, a spring AC tune-up that caught the capacitor at 10 percent low before it failed, and a correct charge verified with gauges rather than guessed. They were sized reasonably. And when a part failed, it was fixed promptly rather than run until it took the compressor with it. None of that is exotic; it is the difference between a system that costs a little each spring and one that costs a lot once.
The R-22 cutoff
If your condenser was installed before 2010, it almost certainly uses R-22, which has not been manufactured or imported since 2020. The system can be repaired, but any repair that requires refrigerant is now expensive because only reclaimed gas is available. A capacitor or contactor on an R-22 unit is still a sensible repair. A leaking evaporator coil or a compressor on an R-22 unit is not; the honest advice is replacement. We walk through this in detail in the R-22 phase-out.
Signs you are near the end
- The system is past 15 years and has had a refrigerant leak repaired once already.
- It cools, but the house never gets below 76 on a 90-degree day, and the compressor amps are above nameplate.
- It is on its second or third capacitor and the compressor is getting a hard-start kit to keep going.
- The DTE bill in July and August has climbed noticeably over a few years with no change in usage; a tired compressor and dirty coils use more electricity for less cooling.
- It is R-22 and has a leak.
- It short-cycles or trips the breaker on the hottest afternoons.
Repair or replace
For a system under 10 years with a part failure, repair. For one between 10 and 15, repair the inexpensive parts and think hard about the expensive ones. Past 15, a major repair is money that could go toward a new matched system with a much higher SEER2 rating and a fresh warranty. Under typical market pricing, a full replacement of a residential split system in our area runs into the mid-four-figures and up depending on size and efficiency, which is why the compressor failure on a 17-year-old unit is where most homeowners draw the line.
Our repair or replace air conditioner guide gives the framework. If the answer is replacement, our AC installation estimates are free and we size from a load calculation, not from the old unit's data plate. New equipment since 2025 uses R-454B or R-32 refrigerant, which changes nothing about how you live with it and improves efficiency substantially over anything from the R-22 era. And if the answer is that the old system has a couple more summers in it, we will say so; a few of our reviews come from people who called expecting a replacement pitch and got a capacitor instead.