Refrigerant Leak Detection: Find It, Fix It, Or Stop Wasting Money

Why 'just adding refrigerant' is malpractice

EPA Section 608 requires technicians to repair leaks above a threshold rate, not just top off the system. Beyond the legal issue: refrigerant is the most expensive consumable in HVAC. R-410A pricing has tripled in five years. R-22 is over $100/lb on the secondary market. A 3-lb recharge today, then again next year, then again the year after, costs more than finding and repairing the leak the first time.

The four-tool leak detection process

We follow a sequence that catches 95% of leaks in one visit.

• Visual: oil staining at every brazed joint, flare, valve, and coil U-bend. Refrigerant carries oil; oil follows the leak
• Electronic: heated diode or infrared detector swept along every joint and the entire coil face
• Soap test: bubble solution on suspect joints found by the electronic detector to confirm
• Nitrogen pressure test: pressurize the system to 350 PSI dry nitrogen, watch for pressure decay over 30 minutes

When we add UV dye and come back

Slow leaks under 1 oz per year often won't trigger an electronic detector. We inject UV-fluorescing dye into the system, run the AC for 48–72 hours, then return with a UV lamp and yellow filter glasses to scan every joint. Dye finds leaks nothing else can.

The big three failure locations on Treasure Coast systems

After fifteen years of Florida service calls we know where to look first. Evaporator coil U-bends from condensate corrosion. Schrader valve cores at the service ports — a $4 part that fails on 1 in 5 systems older than 5 years. Brazed joints inside the air handler that flexed during shipping or install and developed micro-cracks.

Formicary corrosion — the slow killer

Modern aluminum-and-copper coils develop microscopic 'ant-trail' tunneling from VOCs released by new construction materials, certain cleaners, and pool chemicals. It's invisible until refrigerant starts leaking, usually within 5–8 years. There's no repair — the coil must be replaced. We see this constantly in newer homes near St. Lucie West and Tradition.

Repair vs. replace the coil

Single accessible braze joint leak — repair, $300–$600. Multiple coil leaks or formicary corrosion — coil replacement, often warranty-covered. Entire system 12+ years old on R-22 — system replacement saves money long-term. We lay out all three options with honest numbers.

What we do after the repair

Pressure test with nitrogen at 350 PSI for 30 minutes minimum. Pull a deep vacuum to 500 microns, isolate the system, watch for vacuum decay (rises mean residual moisture or a remaining leak). Weigh in the factory charge — never trust pressure-only charging. Verify superheat and subcooling within OEM spec. Document the leak location, repair method, and final charge for your records.