Author: Gerson Mora

We will examine the key points regarding the replacement of R410A refrigerant with R32 gas in a previously operational air conditioning system.

Effect of Replacing R410A Refrigerant with R32 Gas in Compressor:

1. Lubrication

Both R410A and R32 utilize POE oil for lubrication. However, due to their solubility, the POE oil used with R32 tends to have lower viscosity compared to the POE oil used with R410A. Thus, replacing R410A with R32 can, in certain cases, impact lubrication efficiency. The viscosity of the oil within the compressor might be slightly higher than what R32 requires.

2. Amperage

The compressor’s electrical current consumption, or amperage, will be affected by the switch from R410A to R32. Ideally, maintaining the nominal electrical consumption of the compressor, representing the equipment’s characteristics when operating with R410A, is desirable.

Studies have shown that to achieve this nominal consumption value, the system should be charged with only 90% of the specified R410A weight. A charge greater than 90% could lead to an elevated electrical consumption above nominal levels, resulting in abnormal compressor heating and reduced equipment lifespan.

This is because the transition to R32 leads to an increase in the refrigerant’s mass flow rate, resulting in higher discharge pressure. This higher discharge pressure causes an increase in electrical current, and thus, power input.

3. Cooling Capacity

The cooling capacity provided by the compressor will also be impacted by the change from R410A to R32. For instance, considering a 90% load in grams compared to the R410A load, there will be a roughly 10% reduction in cooling capacity. In the graph example, cooling capacity drops from 2.4 kilowatts to 2.2 kilowatts.

Similarly, a 95% load compared to the R410A load leads to a ~5% increase in cooling capacity, but with higher-than-nominal electrical current consumption.

At a 100% load compared to the R410A load, the cooling capacity remains the same as the original equipment, but with higher-than-nominal electrical current consumption.

For a 105% load compared to the R410A load, there’s around a 5% decrease in cooling capacity, with higher-than-nominal electrical current consumption.

4. Discharge Temperature

With this transition, the refrigerant’s temperature at the compressor’s outlet will notably increase, potentially affecting the compressor’s lifespan.

5. Safety

For safety reasons, it’s not recommended to switch from R410A to R32 without manufacturer authorization, even though R32 is slightly flammable.

Here, we present 14 compelling reasons to steer clear of these unfamiliar blends and refrain from introducing any gas other than R22 into the system.

• It can lead to a reduction in cooling capacity.
• It might result in a loss of efficiency, leading to increased electricity consumption. Consequently, this can lead to a rise in the average compressor temperature, impacting the lubricant and the machine’s lifespan.
• There’s a possibility that the discharge temperature of the mixture at the compressor’s outlet will be higher than normal.
• Depending on the blend, issues with lubrication might arise.
• For instance, the combination of gases like R22 and R417A can lead to unpredictable pressures and temperatures, thus negatively impacting efficiency and durability.
• The unpredictability of pressures, temperatures, and the loss of oil return could potentially harm the system.
• Excessive slippage might occur in the resulting blend. Remember, slippage refers to the increase in refrigerant temperature, as observed in the evaporator, for example.
• A high slip value, such as in the evaporator, could result in very high temperatures at its outlet, thereby affecting the cooling process.
• In cases where the mixture has a high slip value, the temperature at the evaporator’s outlet might become excessively high. This could consequently result in a compressor suction temperature above the normal range.
• Even with slight variations in thermal loads, the new mixture could trigger freezing in the evaporator.
• If the system employs pressure switches, abnormal pressures could activate these control devices.
• Some substitutes aren’t compatible with the mineral oil traditionally used with R22, such as R407C, which impacts oil return.
• If the equipment integrates a thermostatic expansion valve, its operation might be compromised as the superheat value measured by the bulb or a sensor becomes unpredictable.
• The environmental impact should not be ignored. Blends affect the atmosphere and the environment. While not illegal, irresponsible usage contributes to environmental harm.

In essence, it’s crucial to avoid preparing refrigerant blends with R22. Each of these points demonstrates that responsible choices and adherence to safe practices are imperative for optimal performance and to safeguard both the equipment and the environment.

We will explore the differences between R22 gas and R422 refrigerant. Let’s get started!

What’s the Difference Between R22 and R422 Gases Used in Air Conditioning and Refrigeration?

• First of all, it’s important to highlight that R22 and R422 are two completely different gases. In fact, R422 has been specifically designed to replace R22 due to the issues caused by R22 to the ozone layer, whereas R422 does not present this problem.
• R22 is a pure gas composed of a single component, while the refrigerants in the R422 family are formed by several components, such as refrigerant R125, refrigerant R134a, and isobutane gas R600.
• Furthermore, while R22 has only one variant, there are several types of refrigerant gases in the R422 family, such as R422A, R422B, R422C, R422D, and R422E.
• Although the gases in the R422 family have the same components, they vary in their proportions’ percentages.
• It’s important to note that R22 can be charged either in liquid or gaseous phase, while the gases in the R422 family must be charged only in liquid phase.
• Within the R422 family, the most recommended gas to replace R22 in air conditioning systems is R422D.
• Additionally, in lower-temperature applications, the R422A refrigerant is widely used as a substitute for R22.
• Both R22 and gases in the R422 family are non-flammable and non-toxic, classified as A1 in terms of safety and belong to group L1.
• These refrigerants are compatible with a variety of lubricants, including mineral oil MO, alkylbenzene oil AB, and polyol ester oil POE.
• However, gases in the R422 family generally have a high temperature glide, meaning their temperature changes during evaporation and condensation.
• In terms of cooling capacity, the R422 family tends to be slightly lower than that of R22, usually with less than a 5% difference.
• In some cases, using gases from the R422 family may require adjusting or regulating the expansion valve.
• A notable difference between R22 and the R422 family is that the discharge temperature at the compressor outlet is lower in R422 gases. This extends the lifespan of the oil and compressor.
• Refrigerants in the R422 family are also known by other names, such as Freon, MO 79, MO 49, MO 29, among others.
• However, not everything is perfect with the R422 family, as they have a relatively high global warming potential (GWP) due to the presence of component R125.

The Capillary for R410A is primarily utilized in air conditioning systems.

These are the 6 main Recommendations for selecting the dimensions of the capillary tube in an air conditioner that operates with R410A.

1. The performance of capillary tubes in the air conditioner depends on both their length and diameter, as these factors determine their total restriction.
   
2. It is essential to consider that a change in diameter, even by a percentage, can impact the flow more significantly than an equal change in tube length.
   
3. Flow restriction can also be adjusted through tube length. When the tube is longer, the flow becomes slower. However, it is crucial to avoid excessively long lengths, as increasing restriction and excessively reducing flow can be uneconomical and inefficient.
   
4. On the other hand, reducing the tube length gradually increases the flow until reaching a critical point, where each further reduction in length causes a faster increase in flow rate.
   
5. It’s important to note that, at the point where the tube is very short, small changes in length can generate significant increases in flow. At this stage, the tube length no longer significantly affects the flow, and the tube acts more like an orifice than a capillary.
   
6. For optimal operation and to avoid issues, it is recommended to maintain the tube length within a range of 5 to 16 feet (approximately 1.5 to 4.9 meters). While there are exceptions to this general rule, in most cases, staying within this range will be beneficial for the daily operation of the air conditioner.

In the following tables, we have the capillary measurements, with diameter in inches and length in meters, for the most common cooling capacities, in BTUs per hour.

Alarm 10 Thermo King can be described in the following table:

Thermoking Fault Code 10:

This alarm is related to higher than normal discharge pressure.

• If the fan is belt-driven, check its condition and tension.
• Inspect the fan gearbox for jammed or worn bearings.
• For electric condenser fan, verify voltage supply and motor behavior.
• Check for a defective 12-volt battery.
• A typical sign of a worn battery is if the unit loses power even before starting the engine.
• Inspect for a faulty High-Pressure Cutout (HPCO) switch. HPCO switch is located on top of the compressor.
• If the unit still doesn’t start, check HPCO switch voltage. Perform a voltage drop test to check for an open circuit. Trace the wiring circuit and verify fuses or switches connected to the circuit.

What to Do with Alarm 10 Thermoking?

In the following video prepared by CST Chilling Systems Training, some recommendations related to Alarm 10 Thermoking are presented:

• Operate the unit in Cooling mode and check discharge and suction gauge readings.
• If the system has a vapor injection for compressor cooling, operate the vapor injection valve to determine if it activates.
• Check the resistance of the compressor discharge sensor.
• The resistance in many Thermo King models should be approximately 86 kilohms at 25°C (77°F).
• However, check your equipment’s sensor type.
• Verify the discharge line temperature using a separate digital thermometer and compare it with the High-Pressure Temperature value displayed in the menu.
• The unit will operate normally without the compressor sensor. However, the compressor’s high-temperature protection from the controller will not be active.

High-Pressure Cutout Switch (Alarm 17):

Thermo King High-Pressure Compressor Switches The High-Pressure Cutout Switch (2) is located on the compressor discharge service valve.

If the discharge pressure becomes too high, the switch opens the compressor contactor’s ground circuit.

The compressor stops immediately.

Evaporator and condenser fans continue to operate normally.

The controller detects that a high-pressure cutout switch or internal protector has been activated.

Verification of the condenser fan is performed.

We are going to develop a comparison between TWO refrigerant gases: the R507A and its substitute, the R448A.

• Let’s start by saying that both the R507A and the R448A are internally composed of a mixture of several gases. Therefore, although the R507A has minimal glide, it is better for both gases to be charged in liquid phase.
• The R-507A is an azeotropic blend, consisting of the gases R-125 and R-143a, each comprising 50%.
• The R507A is known for its chemical stability, good thermodynamic properties, and low toxicity. Its main application is in low and medium-temperature installations.
• On the other hand, the refrigerant gas R448A is composed of a mixture of gases: R32 at 26%, R1234ze at 7%, R134a at 21%, R125 at 26%, and R1234yf at 20%.
• The glide of R507A is very low, and lower than that of R448A. Recall that glide is the temperature change of the gas while changing phase.
• Neither R404A nor R448A harm the ozone layer.
• The R448A has a global warming potential (GWP) of 1387, whereas R507A has a GWP of 3985. Precisely this high GWP value is what condemns the use of R507A due to ecological restrictions.
• R448A is considered a replacement refrigerant for R507A in low and medium-temperature applications in the evaporator.
• The transition from R507A to R448A does not require any modification in the compressor, as the discharge temperature with R448A is very similar to that of R507A.
• R448A is a perfect substitute because it works just as well as R507A with POE type oil.
• R448A is compatible with the components and seals of an existing R507A installation.
• Both R507A and R448A are gases with a safety classification of A1, group L1, meaning they have low toxicity and are non-flammable.

We are going to talk about the type of oil used in an air conditioning unit with a capacity of 12000 BTU per hour, which operates with R410A refrigerant gas.

• Firstly, we must mention that most 12000 BTU per hour air conditioning units use rotary compressors. These compressors are more cost-effective to manufacture, compact, and offer high performance, low noise levels, and acceptable durability.
• Now, it’s time to answer the question: What type of oil does the rotary compressor in a 12000 BTU per hour air conditioning unit use?
• Logically, the characteristics of the lubricant will depend on the compressor manufacturer. However, in many cases, we are not aware of the machine’s technical specifications, and as specialized technicians, we must perform an oil change in the compressor.
• So, the question arises again: What oil should we use when we are not aware of the compressor’s technical specifications and need to perform maintenance by changing the old lubricant?
• In such cases, we can generalize and say that the replacement oil should have similar technical characteristics to the original oil and belong to a reputable brand that guarantees the success of our work.
• Considering the above, the lubricant that we propose as a perfect alternative for these situations is the POE 68 oil, which in most cases is an excellent option to replace the old oil.
• The POE 68 oil has a viscosity close to 68 centistokes at 40°C, which ensures optimal performance at the working temperatures of the refrigerant in the equipment.
• It is essential to remember that oil return can be challenging in split-type air conditioning systems because the oil must travel from the evaporator in the indoor unit inside the room back to the compressor in the outdoor unit outside the room.
• During this process, problems may arise that affect the proper return of the lubricating oil, such as improper inclination or positioning of the return pipes. However, the type of lubricant is crucial for the correct functioning of the equipment.
• When the oil does not return adequately to the compressor, there can be insufficient lubrication, leading to premature compressor wear and a decrease in its lifespan. Additionally, excess oil in the evaporator can affect the system’s performance and reduce its efficiency.
• Not only is POE 68 oil a perfect alternative for rotary compressors due to its quality and viscosity, but it is also important for this oil to have a viscosity stability index close to or higher than 100.
• Let’s remember that the viscosity stability index is a numerical measure that describes how the viscosity of a lubricating oil varies with changes in temperature.
• When a lubricating oil has a viscosity index of 100, it is considered to have very stable viscosity over a wide range of temperatures. As the viscosity index decreases below 100, it indicates that the oil’s viscosity tends to change more significantly with temperature variations.
• In this case, according to the table, this POE 68 oil has a viscosity index of 120.
• So we can conclude that the POE 68 oil not only has the perfect viscosity but must also have the capacity to stabilize this viscosity value.