Refrigerant Leak Repairs Done Right

Refrigerant does not get used up

A sealed system holds the same charge on its last day as its first. If the pressure is low, the refrigerant went somewhere, and "somewhere" is a hole. That sentence is the whole argument against the seasonal top-off. Adding a few pounds every May treats the gauge reading and leaves the hole alone, and in Phoenix the hole is usually growing. If your system is icing, cooling poorly or hissing right now, the refrigerant leak emergency page covers what to check and why to shut the system off. This page explains how a leak is found and fixed properly.

What we measure first

Before a leak search begins, we confirm that the symptom is actually a low charge and not a look-alike.

• Pressures, superheat and subcooling. Low charge produces a specific pattern: low suction pressure, high superheat, low subcooling. Poor airflow across the indoor coil mimics part of it, so airflow and filter get checked at the same time.
• Metering device behavior. A restricted expansion valve or a plugged filter-drier can look like a leak on one gauge and not the other.
• Oil traces. Refrigerant carries compressor oil with it. A wet stain at a fitting or on the coil is often where the search ends.
• System history. How many times has it been topped off, and how much went in each time? A system that took two pounds last year and three this year has a leak that is not going to fix itself.

Only after low charge is confirmed does the search itself start.

How a leak is found

Electronic detection

A handheld sensor traced along every joint, fitting and coil pass. Fast, and good at catching the mid-sized leaks that account for most Phoenix calls. Wind on a roof and a dusty condenser cabinet make it less reliable, so it is rarely the only method.

Ultraviolet dye

Dye circulates with the refrigerant and glows under UV light wherever it escapes. Useful for slow leaks that will not register electronically on a single visit. The cost is time; the dye may need days of run time to reach the leak.

Nitrogen pressure test

The refrigerant is recovered, the system is pressurized with dry nitrogen and watched. If the pressure holds, the leak is somewhere the test cannot reach. If it drops, soap solution and a careful ear find the spot. This is the definitive test, and the one we use when the first two disagree.

Common causes, ranked

Where leaks are found on Valley systems, most frequent first.

• Evaporator coil. Formicary corrosion eats pinholes in copper from the inside, and indoor coils in 155-degree attics see thermal cycling that accelerates it. The most common site and the most expensive to repair, because the fix is usually a new coil.
• Schrader valve cores. The tiny valves inside the service ports. They weep, especially after years of gauge connections. A minor repair when caught.
• Flare fittings. Common on ductless mini-splits. A flare that was under-torqued at installation or has worked loose through vibration leaks slowly and steadily.
• Line set rub-outs. Copper lines vibrating against a stucco wall, a roof jack or each other wear through over a decade. Found by tracing the entire run, including the part hidden in the wall.
• Brazed joints. Factory or field joints that were never quite right. They usually announce themselves with an oil stain.
• Condenser coil. Less common than the indoor coil in a dry climate, but rocks from a mower and corrosion from irrigation overspray both find it.

The R-22 question

If your system was installed before roughly 2010, it may run on R-22, which is no longer produced and grows more expensive each year. A leak repair on an R-22 system means buying reclaimed refrigerant to recharge equipment that is old by any measure. Our guide to R-22, R-410A and R-454B explains the differences, and the R-22 system replacement page covers the path when repair stops making sense. We will tell you which side of that line you are on before recommending either.

Recharging to specification

Once the leak is repaired and the system is evacuated to a deep vacuum, refrigerant goes back in by weight, against the nameplate charge and the line-set length, then confirmed by superheat or subcooling depending on the metering device. "Cold enough" is not a specification. Overcharging damages compressors as surely as undercharging does, which is why the last step of every leak repair is a set of readings, not a feel.

When this repair is worth it

A Schrader core, a flare or a rub-out on a system under ten years old is a clear yes. An evaporator coil on a twelve-year-old R-22 system is a real decision, and our repair-vs-replace guide exists to make it honestly. If replacement wins, the estimate page explains how a quote gets built. And for what it is worth, most slow leaks are found during a maintenance visit in March, when the fix is a core instead of a coil. A web page cannot find your leak or tell you how much refrigerant you have lost. Refrigerant handling requires federal certification and recovery equipment, which is why there is no homeowner version of this repair. An on-site evaluation confirms the charge, finds the leak and quotes the repair flat-rate before anything is opened.