AC refrigerant leak: signs, repair options, and cost

The refrigerant in a central AC moves in a sealed loop. The same charge should last the life of the system. If a technician tells you the system is low, it has leaked, and the useful questions are where and how fast.

Signs of low refrigerant build gradually: the AC runs longer, the supply air is less cold, the electric bill creeps up, and eventually the coil ices over. None of these signs is proof. Dirty filters, dirty coils and weak blowers cause the same symptoms, which is why the charge has to be measured.

Most residential refrigerants have little or no smell at the small amounts involved in a slow leak, so your nose is not a reliable detector.

1. Evaporator coil. The indoor coil's thin tubing can corrode and develop pinhole leaks. This is a common location on systems past their early years. See the evaporator coil replacement cost guide.
2. Service valves and their cores. The access ports on the outdoor unit can seep, and this is the simplest leak to fix.
3. Brazed joints and fittings. Joints at the coils and along the line set can crack from vibration.
4. Condenser coil. Outdoor coils leak from corrosion or physical damage.
5. The line set. Copper lines rubbing on framing, or damaged during other work, can wear through.

The EPA advises repairing leaks instead of topping off a leaking system. Repair keeps the system efficient and avoids paying for the same refrigerant twice. Leak-sealant additives are sold as a shortcut, and many technicians and manufacturers are wary of them, so ask before one goes into your system.

Four things set the bill. The first is the leak search, which can be quick with an electronic detector or slow if the leak is small and hidden. The second is access: a valve core is minutes of work, and a coil is hours. The third is the refrigerant itself, priced by the pound and very different from one type to another. The fourth is the amount needed, which depends on how much escaped and the size of the system. The refrigerant recharge cost guide covers the per-pound side of this.

A fair quote names the leak location, the repair, the refrigerant type and the number of pounds, and states whether the repair carries a warranty.

Refrigerant type weighs heavily. No new R-22 has been made in or imported into the United States since January 1, 2020, so R-22 systems are serviced from recovered and stockpiled supply. The EPA does not require you to replace a working R-22 system, but a major leak repair on one is hard to justify. The guide to the R-22 and R-410A phase-outs explains what that means for your repair bill.