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Aircon Unit Refrigerant And Its Mechanism

What is an Aircon Refrigerant?

Refrigerant is a chemical compound used in your aircon unit. It absorbs environmental heat and provides cool air once it runs through compressors and evaporators. However, there isn’t just one type of refrigerant, which makes it easy to get them confused. There are actually three different types, and using the wrong one can damage your aircon unit because they’re not interchangeable. With that in mind, it’s important to know as much as possible about these refrigerants.

What are the different types of refrigerants?


R-12 is a colorless and odorless CFC refrigerant that was completely banned from production by 1996 under the Montreal Protocol for depleting the ozone. R-12 has many applications in refrigeration and air conditioning including large to medium size chillers, automotive air conditioning, and as an aerosol propellant. R-12 is high-pressure and typically stored in white containers.


R22 is what is commonly known as Freon, and has been used as a central aircon unit refrigerant for decades. However, like R12, it’s been linked to environmental damage such as ozone depletion. As a result, the Clean Air Act of 2010 was passed, and residential furnace repair pros and manufacturers have stopped using it. It has been completely phased out by 2020.


Often referred to by a brand name such as Suva 407C or Genetron 407C. R-407C is a hydro-fluorocarbon (HFC) that does not directly contribute to ozone depletion with a GWP of 1774. Of the higher temperature HFC options, R-407C most closely matches the operating characteristics of R-22, it is a high-glide refrigerant with lower efficiency but provides the simplest conversion from R-22 due to its similar pressures.


R454B is a mildly flammable, lower global warming potential refrigerant designed to replace R410A in new equipment designs. R454B offers the optimal balance of properties to replace R410A in positive displacement, direct expansion air conditioning, heat pump, and chiller applications.


R410A also known as Puron is the R22 replacement for aircon units. Due to the lack of chlorine in the mixture, it’s less harmful to the environment while still retaining the same cooling characteristics as R22. System manufacturers have had great success with R-410A because of its energy-efficient properties and ease of use in their systems. In addition, components are widely available for designing efficient R-410A systems.


R134a or HFC-134a is a non-flammable hydrofluorocarbon refrigerant that was introduced to commercial and industrial applications as an alternative to the R-12 CFC refrigerant. R134a performs similarly to R-12, making it an easy-to-use replacement, and is relatively safe to use as it has an ASHRAE classification of A1. R134a is also known as a tetrafluoroethane (CH2FCF3) since it consists of carbon, hydrogen, and carbon. One of the positives of R134a is that it doesn’t contain chlorine, making it significantly less toxic than R-12.

While R134a is safe to use and a better alternative to R-12, its usage still has a significant impact on the environment. R134a has a 1,430 global warming potential (GWP) rating, which is a measurement of how much heat a greenhouse gas is trapped within the atmosphere versus the amount of heat that’s trapped by CO2. In this case, R134a traps 1,430 times as much heat per kilogram as CO2 does in a hundred-year timeframe, and because of this, the Environmental Protection Agency (EPA) has since listed the refrigerant as “Unacceptable” for certain automotive, commercial, and industrial applications.


R32 refrigerant is also known as difluoromethane and belongs to the HFC family of refrigerants. This gas is poised to replace the other gaseous such as R-410A and R-407C as the preferred gas due to its lower Global Warming Potential. Its chemical formula is CH2F2.

The discovery of the greenhouse effects of refrigerants that are used to replace ozone depletion gaseously has prompted the players in the aircon unit industry to look for better refrigerants. Global Warming is a serious problem that is plaguing the world and the overall temperature of the earth has been rising. This prompted many manufacturers to begin to plan to phase out refrigerants such as R-407C, R-410A, R-134A and replace them with lower GWP such as R32. It has a boiling point of -51°C.

R32 uses 78% less refrigerant to operate compared to R-410A and most newer products in Japan have been phasing in this refrigerant since 2013.

How To Tell Which Refrigerant To Use

One way you can tell which refrigerant your aircon unit needs is by checking the large sticker or plate on its compressor or evaporator, which will state the refrigerant that’s required. It’s important to check these stickers before replacing the refrigerant, as they’re not interchangeable, and using the wrong type can damage your system.

Many aircon units are designed to be used with R-410A for a reliable and more efficient operation. Because R-410A can absorb and release more heat than R-22, and aircon unit compressor can run at a cooler temperature, reducing the risk of compressor burnout due to overheating.

R-410A also functions at a higher pressure than R-22, so new compressors are built to withstand greater stresses, reducing the chance of cracking. If someone were to put R-410A refrigerant into an aircon unit designed for R-22, the pressure could potentially be too high, causing the unit to potentially fail.

Most aircon units use oil to keep the compressor lubricated during operation. R-22 aircon units use mineral oil (MO) and R-410A systems use Polyol Ester Oil (POE). For cases when you are retrofitting a system to an HFC refrigerant, it is recommended to remove at least 95% of the MO before replacing it with POE oil. (NOTE: Under no circumstances should R410a be used to ‘top-off’ an R22 system). POE oil is generally more soluble with R-410A than mineral oil is with R-22. This means the R-410A system operates more efficiently, reducing wear and tear on the compressor.

In addition, temperature glide is a property of some HFC refrigerant blends or mixtures and is generally undesirable. Because the composition alters during a phase change, there is a slight change in evaporating and condensing temperature at constant pressure. Commercial aircon units that use higher glide refrigerants are usually designed to work around the aircon issues associated with glide, with little or no effect on system performance.

As lower GWP refrigerants become available, it’s important to note it may not be possible to use all of them as a retrofit in existing systems because some have mildly flammable properties. Refrigerants should always only be used in systems specifically designed for them, as selected by manufacturers and system designers.

What is the mechanism of an Aircon Refrigerant?

As refrigerant transmutes from liquid to gas and back, it absorbs and releases heat. This is how it is capable of cooling down a home. The compressor changes liquid refrigerant into a high-pressure, high-temperature gas. The refrigerant moves to the outside coil of the aircon unit and releases its heat there through condensation, cooling down. By the time it reaches the indoor coil, it has cooled down to the point that it causes evaporation when it meets the warmer indoor air. This siphons heat from the air, cooling it down. The refrigerant, once again a liquid, returns to the compressor to restart the cycle.

The refrigerant will remain at the same level for the life of the air conditioner—unless leaks occur. If the refrigerant level or charge starts to drop, you will need to have a professional aircon servicing company to repair the system as soon as possible. Low refrigerant will not only lower the cooling ability of your aircon unit, but it can also severely damage the compressor.

About 338aircon.sg

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