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What does a high-pressure gauge reading of 146 psig and a liquid line temperature of 95°F indicate for R134a in the operating system?

  1. A subcooling of 10°F

  2. A subcooling of 15°F

  3. Superheat of 15°F

  4. Superheat of 10°F

The correct answer is: A subcooling of 15°F

A high-pressure gauge reading of 146 psig indicates the pressure of the refrigerant in the system. Coupled with a liquid line temperature of 95°F, this information allows us to calculate the subcooling of the refrigerant. Subcooling is the difference between the liquid line temperature and the saturation temperature of the liquid refrigerant at the given pressure. In this scenario, knowing that the high-pressure gauge reading is 146 psig enables us to determine the saturation temperature of R134a at that pressure. When we find the saturation temperature corresponding to 146 psig, we discover that it is lower than the liquid line temperature of 95°F, indicating a subcooled liquid. The subcooling value, which is the difference between the liquid line temperature and the saturation temperature, is 15°F. Therefore, a subcooling of 15°F is the correct interpretation of the given readings.