Chap. 51 Heating And Air Conditioning Service

A manifold gauge set is a tool used to measure the pressure and temperature of the refrigerant in an air conditioning system. By connecting the gauges to the high and low pressure sides of the system, technicians can diagnose issues such as low refrigerant levels, blockages, or compressor problems. This allows them to accurately assess the condition of the A/C system and determine the necessary repairs or maintenance needed. Therefore, it is true that a manifold gauge set can be used during A/C system diagnosis.

A manifold gauge set is a tool used to measure the pressure and temperature of the refrigerant in an air conditioning system. During the evacuation process, the manifold gauge set can be connected to the system to monitor the pressure levels and ensure that the system is properly evacuated. This is important because a proper evacuation removes any air or moisture from the system, which can cause damage or reduce the efficiency of the A/C system. Therefore, using a manifold gauge set during the evacuation process is necessary to ensure the A/C system is properly evacuated.

Water in an A/C refrigeration system can cause damage because water is not compatible with the refrigerant used in the system. When water enters the system, it can mix with the refrigerant and form acid, which can corrode the metal components of the system. This corrosion can lead to leaks, reduced efficiency, and ultimately, system failure. Therefore, even a single drop of water can potentially cause significant damage to an A/C refrigeration system.

Refrigerant does not condense quickly when exposed to the atmosphere. In fact, refrigerants are designed to be stable and not easily condense at normal atmospheric conditions. They are specifically formulated to operate within a closed system, such as a refrigeration or air conditioning unit, where they can undergo the necessary phase changes to cool or heat the desired space. Therefore, it is incorrect to say that refrigerant condenses quickly when exposed to the atmosphere.

A manifold gauge set is a tool used by technicians to measure and monitor the pressure levels in a refrigeration system. It consists of two gauges, one for the high-side pressure and one for the low-side pressure. By connecting the gauges to the appropriate ports in the system, the technician can accurately determine the pressure levels on both sides of the system. This information is crucial for diagnosing any issues or problems with the system and for ensuring that it is operating efficiently. Therefore, the statement that a manifold gauge set is used to determine both high-side and low-side pressures in the refrigeration system is true.

The statement "R-12 is stored in light blue containers" is false. This means that R-12 is not stored in light blue containers.

When charging an air conditioning system while it is running, the refrigerant should be added to the low side. This is because the low side is the part of the system that is designed to handle the cool, low-pressure refrigerant. Adding refrigerant to the high side could cause damage to the system or result in improper cooling. Therefore, adding refrigerant to the low side ensures that it is properly distributed throughout the system and allows for efficient cooling.

Refrigerant is not lighter than oxygen. In fact, refrigerants have varying densities and can be either lighter or heavier than oxygen. Therefore, the statement is false.

R-134a is not stored in yellow containers.

R-12 and R-134a should never be mixed because they are two different types of refrigerants with different properties. Mixing them can result in damage to the system and potentially harmful effects. It is important to use the correct refrigerant for each specific system to ensure proper functioning and safety.

EPA certification is required to both service R-12 A/C systems and purchase R-12. This means that individuals must have the necessary certification to work on and handle R-12 refrigerant.

Evacuation is the process of removing all traces of air, moisture, and refrigerant from a system. This process is essential in HVAC systems to ensure proper functioning and prevent any damage. By removing air, moisture, and refrigerant, the system can be properly sealed and prevent any contaminants from affecting its performance. This process is typically done using a vacuum pump to create a vacuum and pull out any unwanted substances.

The correct answer is "The liquid line from the condenser outlet to the orifice tube should be cool." This statement is not true because the liquid line should actually be warm, not cool. The liquid refrigerant flows from the condenser to the orifice tube, and it needs to be warm in order to properly boil and evaporate in the evaporator. Cooling of the liquid line could indicate a problem with the system, such as a restriction or a lack of refrigerant flow.

A water flow control valve not opening fully cannot cause excessive heat because if the valve is not opening fully, it means that the flow of water is restricted, resulting in less water reaching the heater. This would lead to a decrease in heat rather than an increase.

Evacuating an air conditioning system involves removing air and moisture from the system. This is because air and moisture can interfere with the proper functioning of the system and can cause damage. However, evacuating the system does not remove dirt particles. Dirt particles can be removed through other cleaning methods such as using filters or cleaning the system components. Therefore, Technician A is correct in stating that evacuating the system removes air and moisture, but Technician B is incorrect in stating that it removes dirt particles.

Warm underhood temperatures actually produce higher than normal A/C system pressures. As the temperature under the hood increases, the refrigerant in the A/C system becomes hotter and expands, causing the pressure inside the system to rise. This higher pressure helps in the cooling process by allowing the refrigerant to absorb more heat from the cabin. Therefore, the statement in the question is incorrect.

When R-12 refrigerant is exposed to an open flame, it will produce phosgene gas. Phosgene gas is a highly toxic substance that was used as a chemical weapon during World War I. It is formed when chlorofluorocarbons (CFCs) like R-12 are burned. Inhaling phosgene gas can cause severe respiratory distress, lung damage, and even death. Therefore, it is crucial to handle and dispose of R-12 refrigerant safely to prevent the release of phosgene gas into the environment.

During an R-12 to R-134a conversion, high and low pressure fittings need to be changed. This is because R-12 and R-134a have different pressure requirements and properties. R-134a operates at higher pressures than R-12, so the fittings need to be able to withstand these higher pressures. Changing the fittings ensures that the system is compatible with the new refrigerant and can operate safely and efficiently.

A manifold gauge set is used when working on air conditioning and refrigeration systems. It is used to measure the pressure and temperature of the refrigerant in the system. This allows technicians to diagnose problems, such as low refrigerant levels or blockages, and make adjustments to the system as needed. The gauge set consists of two gauges, one for high pressure and one for low pressure, connected to the system with hoses. By comparing the readings on the gauges to the manufacturer's specifications, technicians can determine if the system is operating properly or if repairs are needed.

Technician B is correct. The formation of frost on the outside of the line or component indicates a restriction to the flow of refrigerant. This restriction could be caused by various factors such as a clogged filter or a blocked expansion valve. On the other hand, Technician A's statement about the suction line covered with thick frost indicating a flooding expansion valve is not accurate. A flooding expansion valve would result in a lack of frost on the suction line, as the valve would be allowing too much refrigerant into the evaporator.