How long does an evaporator coil last?
Updated August 2026
An evaporator coil lasts 10–15 years, usually reaching the end of its life alongside the air conditioner or heat pump it sits inside. The wildcard is formicary corrosion, a pinhole-eating reaction driven by chemicals in indoor air, which can perforate an aluminum or copper coil in as little as 5–7 years. Once a coil leaks refrigerant it stops cooling, and because the leak is often too small to locate and seal reliably, replacement is the usual verdict at $1,000–2,500 with a recharge.
Lifespan by type and situation
| Type or situation | Typical lifespan | Why |
|---|---|---|
| Coil in a maintained system | 10–15 years | Typically retired with the condenser it was paired with |
| Formicary (pinhole) corrosion | 5–7 years | VOCs from cleaners, new carpet, and building materials eat the metal |
| Frozen and thawed repeatedly | Cut several years | Ice expansion stresses the joints; low airflow or low charge is the cause |
| Dirty coil, never cleaned | Cut 2–4 years | A blanket of dust makes it run colder and ice up, straining the metal |
| All-aluminum coil | 10–15 years | The modern standard; resists formicary corrosion better than copper |
| Coastal or high-humidity home | Low end | Salt air and constant condensate speed up corrosion at the seams |
Signs yours is near the end
- Cooling that fades over weeks as refrigerant slowly bleeds out through a pinhole
- Ice forming on the coil or on the copper line leaving the air handler
- An oily film or residue on the coil or the lines, where leaking refrigerant carries oil with it
- The system running longer and longer to reach the thermostat setting
- A hissing or bubbling sound near the indoor unit from escaping refrigerant
- Electric bills climbing with no change in how you use the system
How to add years
Keeping the coil clean and the airflow strong is what buys the extra years. A yearly coil cleaning stops the dust blanket that makes a coil run cold enough to freeze, and freezing is what stresses the brazed joints until they seep. Change the air filter on schedule so the blower never starves for air, and fix a low refrigerant charge fast, since running low is the quickest route to a frozen coil. Once a coil leaks past its warranty window, weigh a coil-only swap against a full system in the repair-or-replace guide, because on a unit past 12 years the coil rarely goes alone.
What it costs to replace: plan on $1,000–2,500 installed with refrigerant. Replacing on your own schedule, before it fails, is almost always cheaper than the emergency version. The home maintenance cost calculator helps you set the money aside before it comes due.
OnOtto tracks your coil inspections age and service history, and warns you before end of life instead of after the flood.
Track your home's systems, free for 30 daysFrequently asked questions
What is formicary corrosion and why does it ruin coils?
Formicary corrosion is a pinhole-eating attack on the coil's copper or aluminum, driven by volatile organic compounds (VOCs) in the indoor air: cleaning products, new carpet and paint, adhesives, and some building materials. The acids they form bore microscopic tunnels through the metal, and the coil starts leaking refrigerant. Because the pinholes are tiny and scattered, they are nearly impossible to find and seal reliably, so a coil hit by formicary corrosion often fails in 5–7 years instead of the usual 10–15, and replacement is the standard fix.
Is it worth replacing just the evaporator coil?
On a system under about 8 years old, usually yes: a coil-only swap at $1,000–2,500 is far cheaper than a whole new system. Past 12 years the math flips, because the condenser is near the end of its own life and matching a fresh coil to an aging unit is fussy. There is also a refrigerant angle: if your system runs an older refrigerant, a mismatched new coil can underperform. Weigh it with the repair-or-replace guide before you spend.
Why does my evaporator coil keep freezing up?
A coil freezes when it gets too cold or loses airflow across it. The two usual culprits are a dirty air filter or blower starving the coil of warm return air, and a low refrigerant charge from a slow leak. Ice forms, melts, and refreezes, and each cycle stresses the brazed joints until they seep. Change the filter, keep the coil clean, and have a low charge diagnosed quickly. Ignoring it invites the bigger bills in the frozen-coil cost breakdown.
How much does a new evaporator coil cost?
A replacement coil runs $1,000–2,500 installed, including the labor to recover and recharge the refrigerant. The spread comes from coil size, whether it is a cased or uncased coil, and how much refrigerant the system holds. If your unit uses an older refrigerant that is being phased out, the recharge alone can get pricey, which nudges some owners toward replacing the whole system instead of the coil. Ask for the quote itemized so you can see the coil, the refrigerant, and the labor separately.