Your AC Isn't 'Low on Freon' — It Has a Leak: An Honest Guide to Refrigerant Calls

A guy in Valley Glen called me last summer for a second opinion. His AC had been recharged three summers in a row by the same company — about $400 each time. Every May, cold air. Every August, warm air. The tech who kept coming out told him his system was “just getting old and using up its freon.”

That sentence is how you know you’re being farmed.

Refrigerant is not gasoline. Your air conditioner does not consume it, burn it, or wear it out. The refrigerant circuit is a sealed loop — the same few pounds of gas cycle between your outdoor condenser and your indoor coil, over and over, for the life of the system. A properly built system can run 20 years without losing a measurable ounce.

So if your system is low, the refrigerant went somewhere. There is a hole. And every “top-off” you buy without finding that hole is rent paid on the same problem.

Where the refrigerant actually goes

Leaks aren’t mysterious. After ten years of chasing them around LA County, almost every one I find is one of four things:

Formicary corrosion in the evaporator coil. This is the big one, especially in copper coils from the 2000s and 2010s. Volatile organic compounds in ordinary household air — off-gassing from paint, cleaning products, new carpet, pressed-wood furniture — react with moisture on the coil and eat microscopic tunnels through the copper. Under a microscope it looks like ant farms, which is where the name comes from. The result is dozens of pinholes too small to see, each weeping refrigerant. You cannot patch this. A coil with formicary corrosion is done.

Rubbed-out line sets. The copper lines between your condenser and your air handler vibrate a little every time the compressor runs. If an installer let a line rest against a stucco wall, a strap, or another pipe, twenty years of vibration wears through the copper like a rope over a rock. I find these behind condensers and inside wall chases, usually as a single clean hole. These are honestly fixable.

Schrader valves. The little service ports where a tech attaches gauges have spring-loaded cores, same idea as a tire valve. They get old, they seep. A $5 core and 20 minutes fixes it. It is genuinely embarrassing how many “your system needs a recharge” calls turn out to be a leaking Schrader core that three previous techs never checked with a $2 cap of soap bubbles.

Flare fittings and braze joints, mostly on mini-splits and sloppy installs. Mechanical joints loosen; bad brazing pinholes. Findable, fixable.

Notice what’s not on the list: “old age.” Age makes leaks more likely. It is not itself a leak.

The R-22 problem, in dollars

Here’s where the honest math gets brutal for anyone with a system installed before roughly 2010.

Those systems run R-22. Production and import of R-22 have been banned in the US since January 2020 — the only supply left is reclaimed or stockpiled gas, and the price shows it. I’ve seen R-22 quoted at $150-250 per pound in LA this year. A typical residential system holds 6-12 pounds. A system that’s leaked half its charge needs $600-1,500 of gas alone, before labor, before anyone has even looked for the leak.

Now run the scenario I see constantly: a 2005 condenser with a formicary-corroded evaporator coil. The coil can’t be patched, so the “fix” is a new coil — except a new R-22-compatible coil for a 20-year-old system is a unicorn part, and marrying a new coil to a compressor with 20 summers on it means your $2,500 repair is protecting a compressor that’s next in line to die. That’s not a repair conversation. That’s a replacement conversation, and any tech who quietly tops off that system for $900 and drives away has decided your annual payment is worth more than your trust.

R-410A systems (roughly 2010-2024 installs) are a different story. The gas runs $50-90 a pound installed, parts exist, and a repair often pencils out. But 410A is now on its own phase-down — new systems as of 2025 ship with R-454B or R-32, the lower-global-warming-potential refrigerants. 410A won’t hit R-22 prices overnight, but the direction is set. A 410A system is worth fixing today. Its top-offs get more expensive every year you avoid fixing it.

What a real refrigerant call looks like

If a tech tells you the system is low, the very next step is a leak search — not a hose hookup. A proper search means some combination of electronic sniffer on every joint and both coils, nitrogen pressure test with soap solution, and UV dye when the leak is intermittent (dye needs a week or two of runtime, then a return visit with a blacklight). Around here that runs $250-450 as a standalone diagnostic, and dye adds a second trip.

Yes, that’s real money. Compare it to the alternative. Three years of $400 top-offs is $1,200 spent learning nothing, and you still have the leak. One $350 search that finds a rubbed line set behind the condenser turns into a $400-600 braze repair, evacuate, and recharge — and then you’re actually done. I’ve repaired line sets that are still holding charge six years later.

When does a bigger repair make sense? My rough rule: a $600 line or valve repair makes sense on almost any system that’s otherwise healthy. A $1,800-3,000 evaporator coil replacement makes sense on a 410A system under about 12 years old with a strong compressor. The same coil job on a 16-year-old unit, or anything running R-22, is money thrown at a system that’s telling you it’s finished. Put it toward the new one.

Five questions that protect you

Ask these of anyone who quotes you a recharge. The answers tell you everything.

1. “Where is the leak?” If the answer is a shrug, the top-off is a subscription, not a service.
2. “How many pounds did you add, and what does the system hold?” A tech who won’t state pounds added is hiding the size of the problem. Two pounds low on a six-pound system is a serious leak, not a seasonal quirk.
3. “What refrigerant is this, and what’s your per-pound price?” You should know whether you’re buying $60 gas or $200 gas before it leaves the tank.
4. “Did you check the Schrader cores and caps?” Cheapest fix in HVAC. Should be checked first, every time.
5. “If we find the leak, what’s the repair cost — and would you fix it or replace the system?” Then listen. A straight answer references the system’s age, refrigerant type, and compressor health. A dodge references financing.

Refrigerant work is where honest shops and dishonest ones look most different, because the customer can’t see the product. You can’t watch gas go into a sealed loop. All you can do is hire someone whose math you’ve checked.

If your AC has needed a “top-off” more than once, something is leaking and someone should find it. Call or text me at 866-402-5678 — tell me the system’s age and what’s been added before, and I’ll tell you straight whether it’s worth hunting or time to talk replacement.

— Bram