“Regas” is the word most people use when an air conditioning system has lost refrigerant and needs recharging. It comes from car air conditioning, where top-ups are common. A fixed system in a building is different: it’s a sealed circuit, and the refrigerant should stay inside it for life.
This guide explains why a system loses refrigerant, the signs to look out for, what the law says about who can handle it, how a proper leak repair and recharge works, and what to think about if your system uses R410A or R22.
Why a system loses refrigerant
Refrigerant isn’t used up. It circulates round the system, changing between liquid and gas, again and again. If the charge is low, it has escaped through a leak. Common leak points are flare joints at the indoor or outdoor unit, pipes damaged by vibration or rubbing, corroded coils and valves, and poorly made joints from the original installation.
Signs your system may be short of refrigerant
- cooling or heating that has declined gradually over weeks or months;
- ice on the pipework or coil in cooling mode;
- the system running constantly without reaching the set temperature;
- oily marks around pipe joints;
- a hissing sound near the pipework;
- a low pressure or similar error code.
Other faults can look similar, which is why diagnosis comes first. See air conditioning not cooling.
The law: who can handle refrigerant
GOV.UK’s qualification rules say engineers must hold F-Gas qualifications to install, service, leak check or recover refrigerant from air conditioning and heat pumps. Companies doing this work for others must be certified by an approved body. AirCon Doctor is an F-Gas certified company. A DIY top-up kit isn’t a legal or sensible option for a split system.
For larger systems in scope of the leak check rules, a leak must be repaired as soon as possible and the repair checked again within a month.
Want it done properly? AirCon Doctor installs, repairs and services air conditioning and heat pumps across London and the South East, from our base in East Grinstead. We’re an F-Gas certified company and NICEIC approved. Get a fixed-price quote.
Why a top-up alone is the wrong fix
Adding refrigerant without finding the leak means paying for gas that will escape again, and the system runs inefficiently while it’s low. It also releases greenhouse gases. A responsible engineer will tell you if a leak can’t be found or isn’t worth repairing, rather than topping up again and again.
What a proper repair and recharge involves
- Diagnosis. Pressures and temperatures are measured to confirm the charge is low.
- Leak search. Using an electronic leak detector, bubble solution on joints and, where needed, a nitrogen pressure test of each section.
- Repair. Remaking a flare, brazing a joint or replacing a damaged section or component.
- Pressure test with nitrogen to prove the repair holds.
- Evacuation to a deep vacuum to remove air and moisture.
- Recharge by weight, using the nameplate charge plus any extra for the pipe length.
- Records. The refrigerant added and work done go on your F-Gas records.
R410A and R22 systems
R22 is an ozone-depleting refrigerant, and it can no longer be used to top up systems. An R22 system with a leak usually means replacement. R410A is still legal to service, but it has a high GWP of 2088 and supplies are tightening under the GB phase-down, so it is getting dearer. Our guides to repairing or replacing R410A and R22 systems and the 2027 phase-down explain the choices.
What it costs
Because the work depends on what we find, we price regas work after diagnosis. Our repair diagnosis starts from £75 + VAT, and you get a fixed price before the repair goes ahead. See our air conditioning regas page.
Quick answers
How often does air conditioning need regassing?
It shouldn’t. A sealed system keeps its refrigerant for life. If it needs gas, it has a leak, which should be found and repaired.
Can anyone regas an air conditioning system?
No. Engineers need F-Gas qualifications and the company must be F-Gas certified to work on other people’s systems.
Can an R22 system be regassed?
Not with new R22. Its use for topping up has ended, so a leaking R22 system usually needs replacing.
How much does a regas cost?
It’s priced after diagnosis, which starts from £75 + VAT, because the leak repair needed varies. You get a fixed price first.
Related services
More advice
- R410A and R22 Air Conditioning: Repair or Replace?
- R32 vs R410A Refrigerant: What You Need to Know
- The 2027 F-Gas Phase-Down in Great Britain: What It Means for You
- Air Conditioning Not Cooling: Causes and How to Fix It
- Ice on Your Air Conditioning Unit: What It Means and What to Do
- All advice
This guide is general information, checked against the sources linked on 30 October 2026. It isn’t legal, tax or financial advice. Rules, grants and product ranges change, so check the current position before you rely on it.