What is the 404A Refrigerant Operating Pressure in a Walk-In Freezer?

If you want to keep your operation running, a walk-in freezer is a must. But to ensure excellent performance, you need to understand the operating pressure of refrigerant R404A. This topic will show you how the 404A refrigerant works and why it is important to maintain the correct operating pressure. Together with other important details, you will also be able to determine how to measure and adjust the operating pressure of a 404A refrigerant used in your cold storage.


Operating Pressure

What is 404A Refrigerant?

404A is an example of a refrigerant made of hydrofluorocarbons or HFC which is a safe choice because of its non-toxicity and zero-ozone depletion potential. It is environmentally friendly because it does not harm the ozone layer and it is also non-flammable. Some HFCs used in 404A refrigerant are R-125, R-134A, and R-143A which became popular in America and Europe because of its efficiency and long-life cycle when compared with other alternatives.404A Refrigerant



How does 404A Refrigerant Work in the Walk-in Freezer?

The 404A refrigerant is one of the most important components of a refrigeration system because it is the one responsible for transferring heat from one place to another in the walk-in freezer. What makes it efficient is that it can change its property from liquid to gas in a short amount of time. When it starts to absorb heat inside the walk-in freezer, it converts it to gas and then enables it to travel through the compressor. When the gas is inside the compressor, it compresses it to increase the pressure and temperature for it to reach the condenser coil until the heat is released outside. When the released gas comes into contact with the environment, it then condenses back to its liquid state. The high-pressure liquid 404A which was cooled will then flow through the expansion valve. The process will then be repeated continuously to remove heat from inside the freezer.

404A refrigerant’s characteristic to absorb heat is dependent on the pressure level. Lower pressure allows for more efficient heat absorption, which is ideal for maintaining low temperatures in the freezer.

low temperatures



Why is the 404A Refrigerant Operating Pressure Important for the Walk-in Freezer?

To maintain the ideal temperature in your walk-in freezer, pay attention to the 404A refrigerant operating pressure because the lower the operating pressure, the more efficient it will be in absorbing heat keeping the temperature within the ideal level. As I stated earlier, the 404a refrigerant’s ability to absorb heat is dependent on its operating pressure. You will need to adjust the pressure of the refrigerant to regulate the heat absorption but keep in mind that when the pressure increases, the temperature rises.

The ideal operating pressure varies based on the temperature you want to maintain in your walk-in freezer. Keep this in mind, for colder temperatures (such as -10°F), a lower pressure is required compared to slightly warmer settings (like 0°F).



How to Measure the Operating Pressure of 404A Refrigerant in the Walk-in Freezer?

Since 404A refrigerants are chemicals, some potential risks and hazards may occur. Handling and maintenance should be done by licensed and trained professionals. They should also be qualified to work with high-pressure systems.


Operating Pressure of 404A Refrigerant


Steps in Measuring the Evaporation and Condensation Pressure:

  1. Track down the two service ports in your walk-in freezer. These service ports on the refrigerant line indicate “high” pressure and “low” pressure.
  2. Use a leak detector to find if there are any leaks surrounding the service ports. If none, attach the gauges.
  3. The hoses of the manifold should be carefully attached to their respective ports on the freezer. The hoses should be properly connected to prevent leaks.
  4. Do not fully open the valves on the manifold gauge. The opening of the valve should be gradual for the 404A refrigerant to flow through the hoses and gauge properly.
  5. Observe the following pressure readings:
    • Low-pressure side or Suction Pressure is a gauge that shows the pressure of the 404A refrigerant that is entering the compressor.
    • High-pressure side or Discharge Pressure is a gauge that shows the pressure of the refrigerant exiting the compressor.
    •   Sight Glass (optional) makes it possible to see the flow of refrigerant. You will also be able to identify possible problems such as bubbles that indicate a low refrigerant charge.
  6.  A pressure-temperature chart is handy especially for 404A refrigerant because through the chart, you will be able to identify the expected ranges of pressure for both high and low sides depending on the ambient temperature.
  7. Be sure to close the valves on the manifold carefully if you are done with pressure readings. This is to stop the flow of refrigerant and then disconnect the hoses.



Operating Pressure Data Table Reference for 404A Refrigerant

-48°F -44.4°C 0.7 3°F -16.1°C 35.6
-45°F -42.8°C 2 6°F -14.4°C 38.7
-42°F -41.1°C 3.4 9°F -12.8°C 42
-39°F -39.4°C 4.8 12°F -11.1°C 45.4
-36°F -37.8°C 6.3 15°F -9.4°C 49
-33°F -36.1°C 7.9 18°F -7.8°C 52.7
-30°F -34.4°C 9.6 21°F -6.1°C 56.6
-27°F -32.8°C 11.4 24°F -4.4°C 60.7
-24°F -31.1°C 13.3 27°F -2.8°C 64.9
-21°F -29.4°C 15.3 30°F -1.1°C 69.3
-18°F -27.3°C 17.4 33°F 0.6°C 73.9
-15°F -26.1°C 19.7 36°F 2.2°C 78.7
-12°F -24.4°C 22 39°F 3.9°C 83.7
-9°F -22.8°C 24.5 42°F 5.6°C 88.8
-6°F -21.1°C 27 45°F 7.2°C 94.2
-3°F -19.4°C 29.8 48°F 8.9°C 99.8
0°F -17.8°C 32.6 51°F 10.6°C 105.6



How to Adjust the Working Pressure of 404A Refrigerant in Cold Storage?

Adjusting the working pressure of a walk-in freezer system can be a complex task that requires specialized knowledge. Hire the services of a licensed professional to ensure that all adjustments are done correctly. It will also ensure that your cold storage will be safe, efficient, and reliable.

Adjusting the working pressure


The following are the Steps that a Technician would do to Optimize the Operating Pressure of 404A Refrigerant:


Step 1: The technician will assess and evaluate first the performance of the refrigeration system. The things that will be considered are the environmental temperature, load demand, and temperature requirements of your walk-in.


Step 2: The technician will compare the current operating pressure with the manufacturer’s specifications. The comparison is made to see if there are any more adjustments to make.

Step 3: The technician, if he notices that pressure adjustment is necessary will adjust the expansion valve which is responsible for regulating the quantity of 404A refrigerant entering the coil, which then affects the pressure and temperature of the system.

Step 4: Close monitoring of the performance of the unit will be administered by the technician after adjustments to identify if the pressure, temperature, or machine efficiency will experience problems or fluctuations.

Close monitoring

Step 5: If needed or necessary, the technician will adjust the pressure and temperature. This is done to maintain the ideal level of pressure and temperature in the freezer.

Step 6: The technician will record the initial pressure, and the final temperature reading together with all the adjustments done on the system. This will enable the system’s performance to be monitored over time and any recurring issues to be identified more easily.

record the initial pressure



Case Study Analysis

Organic Grocers Fridge Fix: 404A to the Rescue!

The problem: Organic Grocers, known for their vibrant produce, were in a pickle. Their walk-in freezer, powered by the aging R-22 refrigerant (which is bad for the environment!), ceased to function. The temperature experienced fluctuation which resulted in the stored products wilting and increasing their energy consumption at the same time. Since the R-22 refrigerant is starting to be phased out, the company needed a new refrigerant.

Organic Grocers Store


The company chose 404A which is more environmentally friendly but the transition to a new refrigerant did not go well at first. The system needed to be optimized to be efficient. They detected high pressure which strained the compressor of the refrigeration system, and the support of an experienced professional was needed.

The diagnosis: Pressure issue and 404A efficiency blues

Solution: Rain is a technician who checked for leaks, he also inspected the important components, and for the last adjustment, he adjusted the pressure. By using a chart, he was able to identify the ideal setting for 404A. He was able to adjust it to ensure efficient compressor operation while maintaining the ideal temperature.

The adjustment made by Rain was successful. The freezer maintained a temperature (00 C or 320 F) that did not fluctuate which is ideal for preserving the quality of their products. After ensuring the ideal operating pressure level of the new refrigerant, their energy consumption decreased while also contributing to the preservation of the environment.


The Takeaway: Keeping Cool & Eco-Conscious

The scenario shows us a complete transition and the importance of maintaining optimal pressure within a 404A refrigerant system and how it can be achieved with the help of an expert. While adjustments might be needed, qualified technicians can ensure a smooth transition and continued efficiency. Organic Grocers proved you can keep your produce fresh and the planet healthy at the same time.



Frequently  Asked Questions:


1. What is the Difference Between Suction Pressure and Operating Pressure in 404A Refrigerant Systems for Walk-in Freezers?

Working pressure refers to the overall pressure within the system while suction pressure indicates the pressure at the suction line of the compressor.


2.      How to Resolve Common 404a Pressure Problems in Walk-in Freezer?

Common pressure problems may occur when using 404a refrigerant in a walk-in freezer. These problems may arise due to various issues. In such cases, it is highly recommended to contact a professional who can diagnose the problem and ensure that the refrigeration system works efficiently. It is never advisable to attempt to resolve refrigerant-related issues on your own as it can be dangerous and potentially harmful to the environment.

contact a professional


3. How to Maintain Correct Refrigerant Levels in Walk-in Freezers?

Regular inspection is important to maintain the ideal level of refrigerant. Always refer to the guidelines provided by the manufacturer and follow the procedures when recharging. You may use a refrigerant scale to properly measure the volume needed. Over or undercharging will result in potential damage or inefficiency in operation.





The key to any refrigeration system is its refrigerant. You do not have to only choose the most efficient, cost-friendly, and effective refrigerant but you also need to consider its impact on the environment. Currently, in the market, there are a lot of alternatives to choose and there will be a lot more to come out in the succeeding years but the one that leads the refrigerant market is 404A. Its non-flammable, non-toxic, and eco-friendly characteristics are just some of its advantages that will enable you to save on costs, create an efficient and effective refrigeration system, and participate in the reduction of risks on the environment. 

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