San Antonio · Evaporator Coil Repair · Family-Owned Since 1996
If your AC is short on refrigerant year after year and the leak is inside the indoor unit, you've got a leaking evaporator coil. It's a big-ticket repair — but on a younger system, replacing just the coil is usually the smart move.
Typical price
$1,400–$2,800 installed
Time to fix
4–6 hours
Urgency
Medium — system loses cooling gradually
Your evaporator coil is the A-shaped or N-shaped finned coil sitting on top of (or inside) your furnace or air handler. It's where the cold refrigerant absorbs heat from your home's air. When it develops a pinhole leak — and on systems made between roughly 2008 and 2018, they often do — refrigerant slowly escapes until your AC can't cool anymore.
Most coils that fail in San Antonio fail because of 'formicary corrosion' — microscopic tunnels eaten through the copper by chemical compounds in indoor air (cleaning products, off-gassing from new carpet, even certain candles). It's not your fault and it's not anyone's bad install. It's a known industry problem.
The honest math: a coil replacement is $1,400 to $2,800 depending on tonnage and brand. If your system is under 10 years old, that's almost always the right repair. Over 12 years old, we'll usually recommend looking at a full system instead — a new system from $5,999 gets you a 10-year warranty on everything.
What it costs in San Antonio
$1,400–$2,800 installed — Under manufacturer warranty: $600–$1,100 labor only. Includes new coil, filter dryer, refrigerant, and pulling a deep vacuum. Our $59 diagnostic is waived when you approve the repair, so you only pay for the fix itself.
If two or more of these sound familiar, it's probably your evaporator coil.
Here's exactly what a Carnes and Sons tech does at your house — no mystery, no upselling.
We weigh in nitrogen, pressurize the system to 250 PSI, and use an electronic leak detector to pinpoint exactly where refrigerant is escaping. A coil leak is unmistakable — the detector goes off the second it gets near the fins.
Most coils made in the last 10 years carry a 10-year manufacturer parts warranty. We look up your serial number on the spot. If it's covered, you only pay labor.
EPA requires us to recover the existing refrigerant into a recovery tank — never vented to atmosphere. We weigh what comes out so we know exactly how much to weigh back in.
We install the new OEM coil, always replace the liquid-line filter dryer (skipping this kills the new coil), pull a 500-micron vacuum for 30+ minutes to remove moisture and non-condensables, then weigh in the exact factory refrigerant charge.
We measure superheat, subcooling, supply-air temperature drop, and amp draws. You see the numbers on the meter. The system is back to factory-spec cooling.
Get Your Evaporator Coil Diagnosed Today
Tell us what's happening. We'll text you back in minutes — no call center, no robo-calls.
$1,400 to $2,800 installed depending on tonnage (2-ton through 5-ton) and brand. If your coil is still under manufacturer warranty (most are for 10 years), you pay labor only — typically $600 to $1,100. We always check warranty first.
No. Topping off refrigerant on a leaking coil is a temporary patch that costs $300-$500 every summer and gets more expensive as refrigerant prices rise. Plus you're venting refrigerant into the atmosphere, which is illegal under EPA Section 608. Find the leak, fix the leak.
10 to 15 years is typical. Newer coils (post-2018) use better copper and aluminum alloys that resist formicary corrosion much better than the 2008–2018 generation. We back ours with the full manufacturer 10-year parts warranty plus our labor warranty.
Microscopic tunnels eaten through the copper coil tubing by formic acid and similar compounds in indoor air. It looks like ant tunnels under a microscope (hence the name). Common sources: cleaning products, new carpet, certain candles, building off-gassing. It's not from anything you did wrong — it's a known materials problem in coils from that era.
System under 10 years: replace the coil. System 10-12 years old: depends on overall condition — we'll give you both quotes. Over 12 years old or R-22 refrigerant: almost always replace the whole system. A new system from $5,999 with 0% financing often costs less per month than financing a coil repair.
Almost never. The aluminum-to-copper joints on modern coils don't accept brazed repairs reliably, and the fins block access to most leak points. Industry standard is to replace the entire coil — anything else is a temporary fix that fails within months.
4 to 6 hours in most San Antonio homes. We pull the old coil, install the new one, replace the filter dryer, pull a proper deep vacuum (the step a lot of shops skip), weigh in fresh refrigerant, and verify performance. You have cold air back the same day.
Usually yes, as long as the refrigerant type matches (R-410A with R-410A) and the tonnage is the same. We always match the new coil to the outdoor unit's specs — mismatched equipment runs inefficiently, voids the manufacturer warranty, and shortens compressor life.
Most systems installed in the last 10 years carry a 10-year manufacturer parts warranty on the coil. Labor is typically not covered after year 1. We check your serial number before quoting.
We're based in Stone Oak and roll trucks across San Antonio and the surrounding Hill Country every day.
License TACLB29435E · Family-Owned Since 1996
Cities & neighborhoods we serve
San Antonio · Stone Oak · Alamo Heights · Hollywood Park · Hill Country Village · Shavano Park · Castle Hills · Leon Valley · Helotes · Boerne · Fair Oaks Ranch · Bulverde · Timberwood Park · Garden Ridge · Schertz · Cibolo · Selma · Universal City · Live Oak · Converse · Windcrest · New Braunfels
No call center. The owner or one of his sons picks up.
(210) 600-5091