REFRIGERATION SEQUENCE OF OPERATION

A good understanding of the basic operation of the refrigeration system is essential for the service technician. Without this understanding, accurate troubleshooting of refrigeration system problems will be more difficult and time consuming, if not (in some cases) entirely impossible. The refrigeration system uses four basic principles (laws) in its operation they are as follows:

1.“Heat always flows from a warmer body to a cooler body.”

2.“Heat must be added to or removed from a substance before a change in state can occur”

3.“Flow is always from a higher pressure area to a lower pressure area.”

4.“The temperature at which a liquid or gas changes state is dependent upon the pressure.”

The refrigeration cycle begins at the compressor. Starting the compressor creates a low pressure in the suction line which draws refrigerant gas (vapor) into the compressor. The compressor then “compresses” this refrigerant, raising its pressure and its (heat intensity) temperature.

The refrigerant leaves the compressor through the discharge Line as a hot High pressure gas (vapor). The refrigerant enters the condenser coil where it gives up some of its heat. The condenser fan moving air across the coil’s finned surface facilitates the transfer of heat from the refrigerant to the relatively cooler outdoor air.

When a sufficient quantity of heat has been removed from the refrigerant gas (vapor), the refrigerant will “condense” (i.e. change to a liquid). Once the refrigerant has been condensed (changed) to a liquid it is cooled even further by the air that continues to flow across the condenser coil.

The RAC design determines at exactly what point (in the condenser) the change of state (i.e. gas to a liquid) takes place. In all cases, however, the refrigerant must be totally condensed (changed) to a Liquid before leaving the condenser coil.

The refrigerant leaves the condenser Coil through the liquid line as a warm high pressure liquid. It next will pass through the refrigerant drier (if so equipped). It is the function of the drier to trap any moisture present in the system, contaminants, and large particulate matter.

The liquid refrigerant next enters the metering device. The metering device is a capillary tube. The purpose of the metering device is to “meter” (i.e. control or measure) the quantity of refrigerant entering the evaporator coil.

In the case of the capillary tube this is accomplished (by design) through size (and length) of device, and the pressure difference present across the device.

Since the evaporator coil is under a lower pressure (due to the suction created by the compressor) than the liquid line, the liquid refrigerant leaves the metering device entering the evaporator coil. As it enters the evaporator coil, the larger area and lower pressure allows the refrigerant to expand and lower its temperature (heat intensity). This expansion is often referred to as “boiling”. Since the unit’s blower is moving indoor air across the finned surface of the evaporator coil, the expanding refrigerant absorbs some of that heat. This results in a lowering of the indoor air temperature, hence the “cooling” effect.

The expansion and absorbing of heat cause the liquid refrigerant to evaporate (i.e. change to a gas). Once the refrigerant has been evaporated (changed to a gas), it is heated even further by the air that continues to flow across the evaporator coil.

The particular system design determines at exactly what point (in the evaporator) the change of state (i.e. liquid to a gas) takes place. In all cases, however, the refrigerant must be totally evaporated (changed) to a gas before leaving the evaporator coil.

The low pressure (suction) created by the compressor causes the refrigerant to leave the evaporator through the suction line as a cool low pressure vapor. The refrigerant then returns to the compressor, where the cycle is repeated.

Suction

Discharge

Line

Line

Condenser

EvaporatorCoil

Coil

Metering

Compressor

Device

Refrigerant Drier Liquid

RefrigerantLine

Strainer

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Friedrich SS12N10*, SS14N10*, SS15N30*, SS10N10*, SM18N30* service manual Refrigeration Sequence of Operation
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SM18N30*, SS10N10*, SS15N30*, SS12N10*, SS14N10* specifications

Friedrich air conditioners, particularly models SS14N10*, SS12N10*, SS15N30*, SS10N10*, and SM18N30*, are renowned for their reliable performance, innovative technologies, and user-friendly features. Designed for both residential and commercial use, these units stand out due to their energy efficiency, advanced cooling capabilities, and versatile operation.

One of the standout features across these models is their energy efficiency. Equipped with high SEER (Seasonal Energy Efficiency Ratio) ratings, they help users save on energy costs while reducing their carbon footprint. Specifically, the SS14N10* and SS12N10* models excel in cooling efficiency, ensuring that the spaces they occupy remain comfortably cool even in the hottest conditions. This not only contributes to lower energy bills but also promotes environmental sustainability.

The cooling technologies integrated into these units include advanced inverter technology. This feature allows the compressor to adjust its speed according to the cooling demand of a room. As a result, these air conditioners maintain desired temperatures with minimal fluctuations, ensuring optimal comfort and significant energy savings. Models like SS15N30* and SM18N30* are particularly stellar in maintaining efficiency even during peak usage hours.

Moreover, these air conditioners are equipped with multi-stage filtration systems that enhance indoor air quality. The filters effectively capture dust, allergens, and other pollutants, resulting in cleaner and healthier air for occupants. This is especially important for individuals with allergies or respiratory issues.

User-friendly controls add another layer of convenience. Many models incorporate smart technology allowing users to control the units via mobile apps or home automation systems. This feature enables remote operation, scheduling, and real-time monitoring, making it easier to manage climate conditions effectively.

In terms of design, models like SS10N10* prioritize aesthetics without compromising functionality. They feature sleek, modern designs that seamlessly integrate into various decors, whether in a home or an office. Additionally, quiet operation technology reduces noise levels during functionality, enhancing comfort, particularly in bedrooms or quiet office environments.

Overall, Friedrich’s SS14N10*, SS12N10*, SS15N30*, SS10N10*, and SM18N30* models embody the brand's commitment to innovation and customer satisfaction. Their blend of energy efficiency, advanced cooling technology, air quality enhancement, and smart controls positions them as leaders in the air conditioning market, catering to diverse cooling needs while promoting a sustainable future.
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