Problem guide
Refrigerant leak
A sealed system does not use up refrigerant. If it is low, it is leaking.
Get quotes Repair cost calculator
Written by HYRE HVAC Research Desk Primary-source research, data analysis and fact checking
The short answer
A refrigerant leak shows up as weaker cooling, ice on the refrigerant lines or indoor coil, a hissing or bubbling sound, or longer run times. An AC or heat pump is a sealed system and should never need refrigerant topped up.
If it is low, there is a leak. Turn the system off if the coil is icing, and call an EPA Section 608 certified technician to find and repair the leak before any refrigerant is added.
Signs of a refrigerant leak
The house takes longer to cool, or never reaches the setpoint on hot days.
Low refrigerant makes the indoor coil too cold, so moisture freezes on it and on the larger copper line.
A small leak can make a hiss near the indoor or outdoor unit or along the line set.
Refrigerant carries oil, so a leak point can show an oily stain on a fitting or coil.
The system runs longer to do the same cooling.
What you can safely do now
Set the system to off and the fan to on to thaw the coil. Running a frozen system can damage the compressor.
Pull the filter. If you cannot see light through it, replace it. A clogged filter starves the system of airflow. ENERGY STAR suggests checking it monthly in heavy-use seasons.
Most refrigerants have little smell. If you notice a strong chemical smell indoors, open windows and keep people away from the area until a technician checks it.
They do not fix the leak, and some contain sealants that can damage equipment.
Why a top-up is not a repair
EPA rules require Section 608 certification for anyone who works on the refrigerant circuit. Adding refrigerant without finding the leak means it will leak out again, while the system runs undercharged in between. DOE’s 2018 review of field studies found undercharge in a large share of installed systems, which cuts efficiency and capacity.
Newer systems use A2L refrigerants such as R-454B and R-32, which are mildly flammable. Technicians use tools and procedures rated for them. Older systems use R-410A, which can still be serviced.
What a proper leak repair includes
| Step | What happens |
|---|---|
| Find the leak | Electronic detector, bubble solution, UV dye or a pressure test with nitrogen |
| Decide repair or replace the part | Brazed joints and fittings can often be repaired; leaking coils are often replaced |
| Repair | Recover remaining refrigerant, braze or replace, pressure test |
| Evacuate | Pull a deep vacuum to remove air and moisture |
| Recharge to spec | Weigh in the charge or set it by the manufacturer’s method |
| Write it down | Where the leak was, what was done, how much refrigerant was added |
Repair or replace?
A leak at a fitting or valve core is usually a modest repair.
A leaking evaporator or condenser coil on an older system often leads to a repair or replace decision, especially if a new outdoor unit would need a new indoor coil for the new refrigerants.
What drives the price is where the leak is, the refrigerant type and amount, and whether a coil is replaced. HyreHVAC publishes no prices yet; use the repair cost calculator with your quote.
Get connected
Tell us about the work
Three short steps: the job, your home, and how to reach you. Nothing goes to an HVAC company unless you agree.
A person reads it and replies, free and with no obligation. Matching is not live yet, so this is not a quote. If you smell gas or a CO alarm sounds, leave the house and call 911 or your gas utility first.
Get HVAC Options
A person at HyreHVAC reads the request and replies. Matching with contractors is not live yet, so this is not a quote.
Questions
How do I know if my AC has a refrigerant leak?
Is a refrigerant leak dangerous?
Can I add refrigerant myself?
Does an AC need refrigerant every year?
Can a refrigerant leak be fixed?
Written and audited by
HYRE HVAC Research Desk
Primary-source research, data analysis and fact checking
We are a research desk, not a sales floor. We read the federal microdata file, the statute or the manufacturer data sheet ourselves, and we publish the figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify.
The counts below are generated from the published pages themselves, last counted October 26, 2026, and they are what we have actually published rather than what we intend to.
- 18
- studies published
- 15
- federal sources read and cited
- 15
- studies published with their full dataset as CSV
- 51
- jurisdictions reproduced against EIA’s own tables
How this desk works
- Primary sources only. Federal data comes from the agency that collects it, in the file that agency publishes. We do not cite an article that cites a source; we download the source and compute the figure ourselves.
- We validate against the agency before we publish. First, we use each federal microdata file to reproduce the agency’s own published tables. Our cooling research reproduces EIA’s state estimates and standard errors for all 51 jurisdictions. That check caught a variance formula that was off by a factor of four.
- Every estimate carries its uncertainty. These are survey figures, not counts. Standard errors are computed from the replicate weights the federal file supplies and printed beside the estimate. An estimate too imprecise to publish is reported as such rather than printed.
- Nothing is typed by hand. Prose, tables and charts all read from one dataset built by script, so a number in a sentence and the same number in the table below it cannot disagree.
- We publish the data, not just the conclusion. 15 of our 18 studies offer the full computed table as a CSV download on the page, so you can check the analysis or disagree with it. A study without a row-level dataset gets no download link and claims none in its structured data.
- We correct in public. Where we have published a figure wrongly we fix the figure, rewrite any analysis that rested on it rather than patching the number underneath it, and leave a dated correction note on the page.
- We do not install or sell HVAC equipment, and we take no payment for placement, ranking or a favorable mention. Nobody buys a position on this site.
Data as of Sources checked October 26, 2026. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
HyreHVAC is a publisher. We do not install, repair or inspect HVAC equipment and hold no contractor licence. Nothing here replaces an on-site diagnosis by a licensed contractor. Sources are cited with the date they were checked.