This is the failure-mode companion to our main AC repair service. Refrigerant is the most misunderstood — and most overcharged-for — category in AC repair, so this page is blunt about how we handle it.
Why we find the leak before recharging
An air conditioner is a sealed loop. It does not burn or use up refrigerant the way an engine uses oil, so if the charge is low, it leaked out — full stop. Adding refrigerant without fixing the leak just pumps that money into the atmosphere over the next few weeks, and it is an EPA violation to knowingly top off a leaking system without a repair effort. A “recharge special” that skips leak detection is selling you a problem that returns by next month. We locate the leak with electronic detectors and UV dye, repair it, then recharge to the factory weight and verify with superheat and subcool readings.
Signs of a refrigerant leak
- Warm air / never reaches setpoint on a unit that used to cool fine.
- Ice on the indoor coil or copper lines — a low charge over-cools the coil and it freezes.
- Hissing or bubbling near the indoor unit or line set.
- Rising energy bills as the system runs longer to do less.
- Gradual loss of cooling across a season — the signature of a slow leak.
The frozen-coil connection
A frozen evaporator coil is one of the most common ways a refrigerant leak announces itself: the low charge drops the coil below freezing, ice builds, and airflow chokes off until cooling stops. The other cause of a frozen coil is restricted airflow — a dirty filter, dirty coil, or weak blower. Either way, the first move is the same: shut the AC off, run the fan on ON for 60–90 minutes to thaw, and call — running a frozen system risks the compressor. We diagnose which cause it is. Full detail in our frozen evaporator coil guide.
TXV and evaporator coil
Two related sealed-system repairs come up on leak calls. The TXV (thermostatic expansion valve) meters refrigerant into the coil; stuck closed it starves the coil and mimics a low charge, which is why a top-off never fixes it — $585–$895 to replace. A leaking evaporator coil, usually from formicary (pinhole) corrosion, rarely spot-repairs reliably, so the honest fix is a new coil at $1,400–$2,400 matched to your system. On an older unit, a coil leak is often where we run repair-vs-replace math — see AC repair vs. replace.
Refrigerant types — R-410A, R-454B, and R-22
Three refrigerants matter in SoCal right now. R-410A is the standard on most systems installed since roughly 2010; recharge is $85–$145 per pound. R-454B (a low-GWP refrigerant, alongside R-32 in some equipment) is required on most new 2025-and-later residential systems; it costs more, $125–$225 per pound, and requires updated, A2L-rated recovery equipment that many shops do not yet carry. R-22 (pre-2010) is phased out and expensive, so we generally advise against leak repairs that require an R-22 recharge — that money is better put toward a replacement. All of it requires EPA Section 608 certification to handle, which we hold.
Refrigerant repair pricing
| Repair | Typical cost |
| Diagnostic (waived with repair) | $89 / $149 after-hours |
| Leak detection (electronic + UV dye) | $245–$485 |
| R-410A recharge (per lb) | $85–$145 |
| R-454B recharge (per lb, 2025+ units) | $125–$225 |
| TXV replacement | $585–$895 |
| Evaporator coil replacement (coil leak) | $1,400–$2,400 |
We do not quote a refrigerant top-off without finding the leak first — that is the line that separates an honest repair from a recurring bill.
Every major brand
Leaks, TXV faults, and coil corrosion occur across every brand — Carrier, Trane, Lennox, Rheem, Goodman, Daikin, and York AC not cooling cover the brand-specific diagnostics.
Frequently asked questions
How much does it cost to fix an AC refrigerant leak? +
It depends on where the leak is, and our $89 diagnostic ($149 after-hours) credits to the repair. Leak detection with electronic and UV-dye methods runs $245–$485. A leak at an accessible fitting or a Schrader (service) valve is an inexpensive fix plus recharge. A leak inside the evaporator coil is a replace-the-coil conversation at $1,400–$2,400. A failed TXV (the metering valve) runs $585–$895. Refrigerant itself is charged per pound: R-410A $85–$145, R-454B (2025+ units) $125–$225. We find the leak before adding any refrigerant — topping off a leaking system is a bill that lasts weeks.
Why won’t you just recharge my AC with refrigerant? +
Because an AC is a sealed system — it does not consume refrigerant the way a car burns gas. If your charge is low, refrigerant leaked out, and adding more without fixing the leak just sends that money into the atmosphere over the next few weeks. It is also an EPA violation to knowingly top off a leaking system without a repair effort. So we find and fix the leak first, then recharge to the factory weight and verify it with superheat and subcool readings. A contractor who just adds a pound and leaves is selling you a problem that comes right back.
What are the signs of a refrigerant leak? +
The common ones: the AC runs constantly but the house never reaches setpoint, warm air at the vents on a unit that used to cool fine, ice forming on the indoor coil or the copper lines (a low charge makes the coil too cold and it freezes), a hissing or bubbling sound near the indoor unit, and higher energy bills as the system struggles. A gradual loss of cooling over a season usually means a slow leak. We confirm with manifold-gauge pressures and electronic/UV-dye leak detection rather than guessing from symptoms.
Why is my AC freezing up — is that a refrigerant leak? +
A frozen coil has two main causes, and low refrigerant from a leak is one of them. A low charge drops the coil temperature below freezing, moisture condenses and turns to ice, and the ice chokes airflow until the system stops cooling entirely. The other main cause is restricted airflow — a dirty filter or coil or a weak blower. The first step is the same for both: shut the AC off, set the fan to ON for 60–90 minutes to thaw, and call. Running a frozen system can damage the compressor. We diagnose whether it is airflow or refrigerant. Detail: our frozen evaporator coil guide.
What is a TXV and how do I know if mine is bad? +
The TXV (thermostatic expansion valve) is the metering device that controls how much refrigerant flows into the evaporator coil. When it sticks closed it starves the coil — poor cooling, the coil can freeze, and pressures read off — and when it sticks open it floods the coil. It can mimic a low charge, which is why a refrigerant top-off does not fix it. We diagnose it by reading superheat and subcool at steady state against the system’s targets. A TXV replacement runs $585–$895. It is a sealed-system repair, so it includes recovery, replacement, vacuum, and recharge.
Can a leaking evaporator coil be repaired or does it need replacement? +
Usually replacement. Evaporator coils develop pinhole leaks from formicary corrosion (the tiny tunnels that form in copper exposed to certain household chemicals) and from age. Spot-repairing a coil leak rarely holds, so the honest fix is a new coil — $1,400–$2,400 — matched to your system. On an older unit, a coil leak is often the moment we run repair-vs-replace math, because a $1,400–$2,400 coil on a 12-plus-year-old system with degraded efficiency frequently loses to a full replacement. We show you both numbers.
My AC uses R-22 — can you still fix a leak? +
We can, but we usually advise against putting refrigerant money into an R-22 system. R-22 was phased out and is now expensive and only getting more so, which makes any leak repair that requires a recharge a poor investment on an old unit. In most R-22 cases the smarter spend is toward a new system running R-410A or the current low-GWP R-454B. We will tell you honestly when a leak fix on R-22 is throwing good money after bad versus a reasonable stopgap, and we run the replacement comparison so you decide on real numbers.
