Mechanical for A/C Practice Test 2025 – 400 Free Practice Questions to Pass the Exam

To determine the evaporation temperature of R134A at 0 psig, it's essential to understand the relationship between pressure and temperature in refrigeration cycles, commonly represented by refrigerant pressure-temperature charts.

At 0 psig, which is equivalent to atmospheric pressure (since atmospheric pressure is approximately 14.7 psig), R134A is in a state where it can evaporate at a specific temperature. When consulting the pressure-temperature chart for R134A, you would find that the corresponding evaporation temperature at 0 psig is indeed approximately -15 degrees F.

This value indicates the temperature at which R134A absorbs heat from the surrounding environment when it transitions from liquid to vapor in the evaporator. Knowing this temperature is crucial for designing and troubleshooting A/C systems, as it helps ensure the refrigerant operates efficiently and effectively. Thus, the selected answer is valid and supported by the properties of R134A as indicated on the pressure-temperature chart.