AC Refrigerant Types Explained: R22, R32, R410A and More

Your air conditioner runs on refrigerant, but most people never think about it until something goes wrong. Whether your unit is losing cooling power, making unusual sounds, or a technician has told you your refrigerant is low, understanding the different types and what they mean for your system is genuinely useful knowledge. This guide covers all the main refrigerant types used in residential and commercial air conditioning, explains the environmental regulations driving the industry's shift away from older coolants, and helps you understand what your own unit is running on.

What Is AC Refrigerant and How Does It Work?

Refrigerant is the substance that makes air conditioning physically possible. It circulates continuously through your AC system, absorbing heat from the indoor air and releasing it outside. This happens through a cycle of compression and expansion: the refrigerant evaporates inside the indoor unit, absorbing heat in the process, then gets compressed and condenses in the outdoor unit, releasing that heat outside.

The type of refrigerant in your system determines its operating pressure, energy efficiency, environmental impact, and compatibility with specific components. Using the wrong refrigerant, or topping up a system with a different type, can damage the compressor, cause leaks, and in some cases void your warranty. This is why knowing your unit's refrigerant type matters every time you book a service or consider replacing an older unit.

Refrigerant Comparison at a Glance

Refrigerant	Type	Ozone Depletion	GWP	Flammability	Status
R22	HCFC	Yes	1,810	None (A1)	Being phased out
R410A	HFC blend	No	2,088	None (A1)	Being phased out
R32	HFC	No	675	Mildly flammable (A2L)	Current standard
R290	Natural hydrocarbon	No	20	Highly flammable (A3)	Growing adoption

The Main Types of AC Refrigerant Explained

R22 (Freon)

R22, also known as chlorodifluoromethane, is a hydrochlorofluorocarbon that was widely used from the mid-20th century. For decades it was the standard refrigerant in residential and commercial air conditioning, valued for its high cooling efficiency and low cost.

The problem is its environmental footprint. As an HCFC, R22 is categorised as an ozone-depleting substance. Under the Montreal Protocol, the production and consumption of HCFCs in manufacturing industries will be phased out by 2030. The production and import of R22 were phased out in many countries starting in 2010, with a complete ban in effect since 2020 in the United States due to its ozone-depleting potential.

If you own an older air conditioner in Hong Kong, it may still be running on R22. These units can continue to operate, but strict measures are required to control leaks when servicing existing equipment. Topping up an R22 system is becoming increasingly expensive as supply diminishes, and replacement parts are harder to source. For homeowners with R22 units, planning ahead for eventual replacement is the practical course of action.

R410A

R410A, a hydrofluorocarbon blend of difluoromethane and pentafluoroethane, was introduced in the early 1990s and became the standard for residential and commercial air conditioning systems in many parts of the world due to its superior efficiency and safety profile compared to R22.

Unlike R22, R410A does not deplete the ozone layer. R410A is composed of R32 and R125 in the proportion of 50% each by mass fraction, has a safety level of A1, and is non-combustible, non-explosive, and very low in toxicity.

However, R410A has its own environmental problem. R410A has a GWP of 2088, both much higher than new regulations permit, and is being phased out under new regulations. For cost-sensitive markets without strict GWP rules, R410A is still acceptable, but long-term planning should shift to R32 or R290. Many units installed in Hong Kong between 2000 and 2020 run on R410A, and these systems will remain serviceable for years to come, but new installations are increasingly moving toward lower-impact alternatives.

R32

R32 has lower GWP, high energy efficiency, and better environmental performance than R410A, and is now mainly used in new residential AC systems, particularly in Asian markets.

R32's refrigerating performance is comparable to R410A, but it requires approximately 30% less charge for the same cooling capacity. As a straight R410A system replacement, R32 has around 10% more capacity, meaning a new system built for R32 will deliver higher cooling capacity, or require smaller displacement compressors to achieve the same capacity.

R32 is classified as mildly flammable (A2L), but with proper handling and installation, it poses no significant risk. Its GWP of 675 is roughly one third that of R410A, making it a significantly more responsible choice from an environmental standpoint. R32 is now the standard refrigerant in most new split type units sold across Hong Kong, Japan, and much of Europe.

R290 (Propane)

R290, chemically known as propane, is a natural refrigerant with very low toxicity and a GWP of 20, meaning it has minimal impact on global warming. It is a natural organic compound derived directly from liquefied petroleum gas, making it cost effective.

From a pure environmental standpoint, R290 is the most responsible option currently available for residential air conditioning. R290 is less expensive than R134a, and its GWP is much lower than R134a or R410A.

The significant drawback is flammability. R290 has a safety classification of A3 and an explosion limit of 2.1% to 10.0%, which is lower than R32, and rigorous safety measures are essential during use to ensure the refrigerant charge remains within regulatory limits. Due to this constraint, R290 is primarily used in small residential AC units and portable air conditioners rather than standard split systems. Its adoption is growing, but it requires specifically designed equipment and trained technicians to handle safely.

What Refrigerant Does My Air Con Use?

The quickest way to identify your unit's refrigerant type is to check the label on the outdoor compressor unit. Manufacturers are required to print the refrigerant type on this label, typically next to the model number and electrical specifications. Common labels include R22, R32, or R410A followed by the required charge weight in grams.

As a general guide based on the installation period:

• Units installed before 2000: Almost certainly running on R22.

• Units installed between 2000 and 2018: Likely R410A, possibly R22 in older stock.

• Units installed from 2018 onward: Most likely R32, particularly for split type units from brands like Daikin, Mitsubishi, Panasonic, and Hitachi.

If you are unsure, a qualified technician can confirm the refrigerant type during a routine service. Our AC cleaning services in Hong Kong include a unit inspection as part of each visit, which gives you the opportunity to confirm the refrigerant type and check for any signs of leakage at the same time.

What to Do If Your AC Refrigerant Is Low

Low refrigerant is one of the most common reasons an air conditioner stops cooling effectively, but it is not something that can be resolved with a simple top up.

Refrigerant does not get consumed by normal operation. If your system is running low, it means there is a leak somewhere in the system that must be identified and repaired before any refrigerant is added.

Signs that your refrigerant may be low include reduced cooling output despite a clean filter, ice forming on the indoor unit or copper pipes, a hissing or bubbling sound from the outdoor unit, or the unit running continuously without reaching the set temperature.

Refrigerant handling is regulated work in Hong Kong. Only qualified technicians are permitted to handle, add, or remove refrigerant from AC systems. Attempting to add refrigerant without locating and repairing the leak first will result in the same problem recurring within weeks. If you suspect a refrigerant issue, the correct course of action is to book a professional inspection rather than delay. You can check AC cleaning and servicing prices in Hong Kong to understand what a full inspection and service typically costs before contacting a provider.

Homeowners with older R22 units facing a refrigerant leak should take the opportunity to weigh up whether repair or full replacement makes more financial sense. Given the increasing scarcity and cost of R22, a unit that requires repeated top ups may cost more to maintain than a new R32 system would over the same period.

FAQs About AC Refrigerants

Can I top up my own AC refrigerant at home?

No. Refrigerant handling requires specialist equipment and certified training. In Hong Kong, refrigerant must be handled by a qualified technician in accordance with electrical and mechanical services regulations. Adding refrigerant without first locating and repairing a leak will not solve the underlying problem and may create additional issues with system pressure.

Is R32 safe for home use?

Yes. R32 is classified as mildly flammable (A2L), but with proper handling and installation, it poses no significant risk. The concentration required to create a flammability hazard is far higher than what could realistically accumulate in a domestic space under normal conditions. All new split type units sold in Hong Kong that use R32 are designed and certified to handle it safely.

Can I replace an R22 unit with an R32 unit?

Yes, and in most cases this is the recommended course of action for ageing R22 systems. The new unit will use different pipework specifications and components, so it is not a direct swap of refrigerant into an existing system. A full unit replacement is required, after which your running costs and environmental impact will both improve considerably. You can learn more about what a new installation involves through our AC installation service page.

Will my R410A air con become illegal to use?

No. Phase out regulations apply to the production and import of high-GWP refrigerants, not to the use of existing equipment. Your R410A unit can continue to operate legally for its full service life. The restrictions affect new manufacturing and the restocking of refrigerant supplies, which means servicing older systems will gradually become more expensive as availability decreases.

How do I know if my AC has a refrigerant leak?

The clearest signs are reduced cooling performance despite a clean filter, ice forming on the indoor unit or connecting pipes, an unusual hissing sound from the outdoor unit, and electricity bills rising without a change in usage patterns. Any combination of these symptoms warrants a professional inspection. Regular split AC servicing includes a check of the system for signs of leakage as a standard part of the process.

How long does refrigerant last in an AC system?

A properly sealed AC system should retain its full refrigerant charge for the entire lifespan of the unit, which is typically ten to fifteen years. Refrigerant does not degrade or evaporate under normal operation. If your system needs refrigerant added on a recurring basis, this is a reliable sign of a persistent leak that requires professional diagnosis and repair.