Which symptom indicates a leak in a high pressure system that utilizes a capillary tube?

In a high-pressure system that utilizes a capillary tube, excessive superheat is a key symptom that indicates a potential refrigerant leak. The capillary tube functions by regulating the flow of refrigerant into the evaporator; if there is a leak, the refrigerant levels will drop, leading to insufficient refrigerant in the evaporator. As a result, the refrigerant does not absorb enough heat, and the temperature of the vapor leaving the evaporator increases, causing excessive superheat.

This situation can lead to further operational issues within the system. An adequate amount of superheat is necessary to ensure that only vapor enters the compressor; however, if superheat levels are excessively high, it may indicate that the evaporator is not filled adequately with refrigerant due to the leak. Understanding this symptom helps technicians identify problems effectively and take corrective actions.

While symptoms like low superheat, high discharge temperature, and rapid cycling of the compressor are also important indicators of system conditions, they are not as directly aligned with identifying refrigerant leaks in systems using capillary tubes as excessive superheat is.