Low refrigerant shows up as warm or weak air, ice on the coil or lines, hissing, long run times and higher bills. Your AC never uses refrigerant up, so low charge means a leak. For a diagnosis, call (541) 461-2101 in Eugene, Springfield and Lane County or (503) 581-9982 in Salem, Keizer and Marion County.
What are the signs of low refrigerant in an AC?
Low refrigerant in an AC shows as warm air, long run times, ice, hissing, oily residue, higher bills and a house that misses the setpoint.
No single sign proves it. You’re looking for several, building over weeks. We check each one against the faults that mimic it, because a failed capacitor or a dirty coil can look like low charge. The table shows how.
| Sign | What you notice | Could also be | How we confirm it |
|---|---|---|---|
| Warm or weak air | Vents blow air that is cool, not cold | Dirty filter, failed capacitor, blower fault | Temperature split across the coil |
| Long run times | AC runs most of the afternoon and evening | Undersized system, dirty coil | Pressures and superheat |
| Ice on the coil or lines | Frost on the copper lines or indoor coil | Airflow blockage, cool night with a low setpoint | Subcooling after a full thaw |
| Hissing or bubbling | Noise near the lines or indoor coil | Rarely anything else | Leak detector at the noise |
| Oily residue | Dark, oily film at a fitting or on the coil | Old lubricant stain | Electronic or dye test at the spot |
| Higher bills | Power use climbs with no change in habits | Rate changes, dirty coil | Compare readings to the nameplate charge |
| Thermostat never reaches setpoint | House stays a few degrees warm | Duct leaks, poor insulation | Full system check |
If several of these match your house, refrigerant has gone somewhere. Where does it go in a sealed system?
Why does an AC lose refrigerant if it is a sealed system?
An AC loses refrigerant only through a leak, because a sealed loop holds the same charge for the life of the system.
The compressor pushes hot refrigerant to the condenser, the metering device drops its pressure, and the evaporator coil absorbs the heat from your indoor air. Nothing in that loop consumes refrigerant, so a charge that falls is a charge that escaped. A slow leak can fade your cooling over a season instead of failing in a day.
Leaks cluster at flare fittings, Schrader valves, line set connections and pinholes in the evaporator or condenser coil. We inspect those spots first on every leak call.
A leaking system costs more than comfort. Ice on the coil can send liquid refrigerant back toward the compressor, the part we least want to damage. If you see frost, switch cooling off, and we test the coil before the system restarts. Which problem made that frost?
Does low refrigerant cause ice, or is it low airflow?
Low refrigerant can cause ice on your AC, but low airflow does too, and the two look alike until we test the charge with gauges.
HVAC School says low charge often gives a partially frozen coil rather than a full block of ice, with frost building at the start of the coil after the metering device. A dirty filter, a closed return or a weak blower freezes the coil as well. That’s why “low freon” is a wrong guess more often than people expect.
Gauges separate them. HVAC School describes low charge as low suction, low subcooling, high superheat and low head pressure. Low airflow gives low suction, low superheat, low head pressure and a high temperature drop across the coil. A restriction in the line shows high subcooling instead. We check all of those numbers together, because pressure alone misleads.
Start with the free checks before you call. We run the same four first on every cooling call.
- Replace a grey filter.
- Open every supply register and the return grille.
- Clear leaves and debris from around the outdoor unit.
- If you see ice, switch cooling off and thaw the frozen evaporator coil before anything else.
- Run the AC again. If cooling stays weak, or ice returns after a new filter, charge is the next suspect, and we test it next. The wider list of causes is in why an AC blows warm air.
Once the gauges say low charge, how does the leak get found?
How does a technician find a refrigerant leak?
A technician finds a refrigerant leak with an electronic detector, UV dye or bubble solution at the suspect joints, then repairs it before any refrigerant goes back in.
We run the same order on every leak call.
- Airflow. We check the filter, return, blower and coil face first.
- Temperature split. We test the temperature drop across the coil.
- Superheat and subcooling. We run the pressure readings and calculate both.
- Leak search. We test the suspect joints with a detector, dye or bubble solution. A nitrogen pressure test can show a leak too small to find by sound or sight.
- Repair and vacuum. We repair the leak, then pull a vacuum to remove air and moisture.
- Recharge. We charge the system with the refrigerant it was built for, then check the readings again.
Skip the leak search and the system loses its charge again. That is the whole problem with a recharge alone. Can you do the recharge yourself?
Can I add refrigerant to my AC myself?
No. EPA’s Section 608 sales restriction lets only certified technicians, and employers who can show they employ one, buy refrigerant for stationary equipment.
Without gauges you can’t read superheat or subcooling, so you would be guessing at the charge of a leaking system. A system also takes only the refrigerant it was designed for, so you can’t swap one for another to save money. Our technicians hold Section 608 certification, and we repair the leak before we add any refrigerant. Which refrigerant does yours take?
Which refrigerant does my AC use, and can it still be repaired?
Your AC’s refrigerant follows its age, with R-22 in systems built before 2010, R-410A in the generation after, and R-454B or R-32 in new equipment from 2025.
Age is the quick guide, and a leak can be repaired on any of them. The EPA’s consumer page on repairing home AC lets units made before 2010 keep being serviced with R-22, and the EPA requires no replacement.
| Refrigerant | Typical systems | Status | What it means for a leak repair |
|---|---|---|---|
| R-22 | Built before 2010 | Production and import ended January 1, 2020 | Existing systems can still be repaired with reclaimed or recycled R-22; EPA requires no replacement |
| R-410A | Built after R-22 systems, before 2025 | New systems made from January 1, 2025 can’t use it under the AIM Act rules | Existing systems stay serviceable; EPA says repair parts for existing systems aren’t covered by the new limits |
| R-454B or R-32 | New equipment from 2025 | Current for new residential systems | Service by a technician trained on these refrigerants |
The AIM Act limit on new equipment appears in EPA’s HFC restrictions by sector table. We service R-22 and R-410A systems already in homes, and newer equipment uses R-454B or R-32. What will the leak repair cost?
How much does a refrigerant leak repair cost?
National cost guides put a refrigerant leak repair at $200 to $1,600, including the leak search and the recharge, and the leak’s location moves the number most.
These ranges are guides, not quotes, and we quote your actual repair in writing.
| Item | Range | Source |
|---|---|---|
| Leak repair including leak search and recharge | $200 to $1,600, average $800 | Fixr, July 2026 |
| Leak repair, any location | $200 to $1,500+ | This Old House, March 2026 |
| Recharge only, central AC | $150 to $600 | This Old House, April 2026 |
| R-410A per pound, installed | $50 to $80 | This Old House |
| R-22 per pound, installed | $90 to $150 | This Old House |
| Refrigerant recovery fee, if billed separately | $30 to $100 | This Old House |
| Line set replacement | $200 to $700 | This Old House |
| Evaporator coil replacement | $627 to $2,700, average $1,350 | This Old House, April 2026 |
| Condenser coil replacement | $1,000 to $2,700+ | This Old House, March 2026 |
Neither guide prices a leak search by itself, because the repair folds it in. They don’t list R-454B or R-32 per pound either, so a system on those refrigerants needs a written quote. Per-pound R-22 figures also differ between sources, a sign of tight supply. We quote a firm price after we inspect your home, and we explain where the leak is before any refrigerant goes in. When the number climbs, is it still worth fixing?
Should you repair or replace an AC with a refrigerant leak?
Repair the leak when it sits at a fitting or valve on a younger system, and replace the AC when the repair costs more than half of a new one.
The U.S. Department of Energy’s Building America guide sets that half-the-cost rule, and a repair costing more than half of replacement means replace. A coil leak on an old R-22 system usually fails that test, because a coil costs far more than a connection and R-22 costs more per pound. We quote both the repair and the replacement, and we run that math with you.
Two more things count. We check whether this is your first leak or your third, and we price the refrigerant itself. Nobody is required to replace an R-22 system, so the choice is yours. When the repair approaches the price of new equipment, compare options in our new air conditioner cost guide.
Call us about a leaking or underperforming AC
We diagnose cooling problems on every AC repair call and quote in writing before work starts. James Heating and Air Conditioning serves the Willamette Valley since 1983 and holds Oregon CCB #47396.
- Eugene, Springfield and Lane County, (541) 461-2101.
- Salem, Keizer and Marion County, (503) 581-9982.
We answer around the clock. Tell us what your AC does and when, and we test for charge, airflow or something else.
Frequently asked questions
What happens if AC refrigerant is low?
Cooling drops, run times stretch and the coil can ice over. Liquid refrigerant can reach the compressor, so switch cooling off if you see frost. We test the charge before the system runs again.
Can an AC run with low refrigerant?
It will run, but poorly. Cooling fades, the system runs longer and the coil can ice over. We check for frost first, so switch cooling off if you see any and call us.
Will low refrigerant raise my electric bill?
It can. A leaking system runs longer to reach the setpoint, so it uses more power. We check your readings against the nameplate charge to see how far off the system is.
How long does refrigerant last in an AC?
It lasts for the life of the system. The loop is sealed and nothing consumes the refrigerant, so there’s no refill schedule. If your AC needs more, we inspect the system for the leak.
Should I keep running my AC if I see frost on the lines?
No. Switch cooling off and let the coil thaw, then call us. Running a frosted system risks the compressor, and we diagnose the cause before it runs again.
