Type to search

How To Add R22 to Central Air Conditioner


In the previous articles, we talked about the different parts of window-type and split-type air conditioners. While most air conditioners have the same inner and outer mechanism, there are distinct differences that separate one model from another.

However, the main reason air conditioners are capable of cooling our indoor environment is because of refrigerants. These function by absorbing the heat in their surroundings and converting the warm temperature into a fresh and cool one as it passes through the compressor and evaporator. 

The most commonly used refrigerant is called an R22, also known as Freon. But what is it made of? How to add R22 to a central air conditioner? Can I do it myself? And are there other types of refrigerants? Let’s find out.

What is R22?


An R22 refrigerant is the most popular type of cooling agent used in an air conditioning system. It’s also commonly known as Freon in the market. It can maintain cool and fresh air because this chemical absorbs the heat in the air. It then changes from a hot liquid to warm vapor as it passes through the evaporator coil, leaving only the cooled air.

Your air conditioner’s refrigeration system is a closed-loop system because the refrigerant continuously circulates from your outdoor condenser into your indoor evaporator coil. As long as the refrigerant is kept at the proper level, it keeps working.

Much like other refrigerants, R22 is a non-flammable gas that is compressed into liquid form inside an AC unit to cool the air inside our homes. These gases, despite being toxic in small doses, can result in serious health issues when consumed in large quantities and can pose a serious refrigerant leak.

What Causes the R22 Refrigerant to Run Out?

An R22 refrigerant is not invulnerable to damage if there is a potential risk that can cause it to burst out of the air conditioner. While it does not necessarily run out, it needs to be replaced immediately if it starts to leak from the air conditioning unit.

A refrigerant leak is a common cause for the R22 to run out. You can notice this if the system is taking too long to cool your house. The warmer air that your central air conditioner is blowing could also be a sign of refrigerant canister damage. If your unit starts hissing, there is probably a significant leak. If this happens, it’s best to consult a certified HVAC technician so they run a full diagnosis of your air conditioner.

If the air conditioner is left unused for a very long time, dust and mold will start to build up inside the system. This affects, not only the AC parts but also the R22 itself. It cannot absorb heat effectively if the air filter, manifold hoses, valve caps, and refrigerant hose are clogged. Thus, proper maintenance of the air conditioner needs to be strictly followed.

Moreover, if the evaporator and condenser coil, blower wheel, and filters are dirty, then these can be signs of low refrigerant in the AC unit. It can also cause the release of unwanted warm air inside the house. It also makes the need to add refrigerants difficult. Refilling the R22 canister under the said conditions will further damage the unit.

Can I Add Freon to My Air Conditioner Unit Myself?

The answer is no. Freon can cause serious health problems if it’s handled unprofessionally. It’s better to ask a professional HVAC technician to do the job to avoid unnecessary damage to your air conditioning unit. 

Additionally, it’s also a risk to the environment, especially to the ozone layer. It’s a major contributor to global warming because it contains chemicals that break down the ozone molecules faster. It means that an R22 cooling agent can deplete the ozone layer much faster than other greenhouse gases like carbon dioxide.

How Do HVAC Technicians Add R22 to a Central Air Conditioning System?


If you notice any refrigerant leak from your aircon, then it’s best to consult an expert to assess the situation. They have all the equipment needed to fix an aircon. Here are the common steps that a professional aircon technician follows when adding refrigerant to a central air conditioner.

  1. The AC unit is turned off by setting the thermostat to its coolest setting and shutting down its switch at the circuit breaker.
  2. Since this is a central aircon, the R22 refrigerant can be found in the outside unit. The R22 valve caps are removed and carefully placed on a clean surface. The technicians also check the user’s manual because there are models that may require an adjustable wrench to remove the valves.
  3. Most of the time, the valve has a small knob at the bottom left side so it can be opened more easily.
  4. The R22 refrigerant container has two manifold gauges. The left-hand hose is connected to the large pipe valve, while the right-hand hose is connected to the small pipe valve.
  5. Pressure is purged from the manifold by connecting the third refrigerant hose to the canister and the two connected handles are opened every four to five seconds.
  6. To equalize the pressure inside the container, the R22 manifold hoses are connected to the refrigerant container and flipped upright to open the valve. 
  7. The left and right-hand gauges are watched to see if the pressure is at equilibrium. 
  8. The left-hand gauge should read below 60 psi, indicating a low-pressure valve. 
  9. The system is allowed to run for three to five minutes then the temperature gauge is monitored as excess R22 is released. The technicians make sure it doesn’t equalize with the outdoor temperatures.
  10. Using a thermometer placed at least 6 inches from the valve from the large pipe, the super-heat temperature is measured. This will help get an accurate reading of the temperature and pressure of the R22.
  11. The results are compared to the left-hand gauge pressure and it is determined if it follows the recommended pressure from the manufacturer’s manual.
  12. After a certain amount of refill has been done, the hoses are disconnected and the valves replaced.

Do You Add R22 as a Liquid or Vapor?

When you recharge your aircon because it runs out of cooling agent and needs a refill, R22 and other pure refrigerants can be added as a liquid or vapor gas. If you’re adding liquid to the suction line, do so gradually to prevent sluggish operation of the compressor or dilution and contamination of the compressor oil. Furthermore, consult with your aircon technician to determine if there are other additional services, like aircon repair, that need to be done.

Final Thoughts


Most of the time, we can maintain the good condition of our aircon without the need to hire a professional. However, when it comes to refilling the cooling agent, it’s best to ask someone who is capable of the job. This is the golden rule that you should always follow, especially when it comes to older units.

An R22 cooling agent is non-flammable and is compressed inside a container. The only time we need to refill it is if we hear any hissing sound from the aircon. This incident is usually an indication that there are potential gas leaks. Most aircon systems have dedicated pipes to resolve the situation, but they need immediate repair to avoid any added cost. 

Moreover, fixing them on your own might worsen the situation, especially if you don’t have the right tools and enough experience to add an R22 cooling agent to your aircon.

JP Reyes

JP has been in the aircon industry for almost as long as he has been alive. As a child JP would help his tatay fix aircon units at their junk shop in Cavite. After graduating UP in the early 2000's, JP then started his own Aircon servicing business and within 5 years had 10 shops in 8 different cities. Fast forward to today and JP brings all his experience and expertise online to give readers trustworthy advice and reviews about Air-conditioning buying, servicing, cleaning and repair in the Philippines.

  • 1