Air Conditioning Repair Certification (ETI) Practice Exam

To determine the approximate pressure of R-134a vapor leaving the condenser after being sub-cooled by 20°F, it's important to consider the relationship between temperature and pressure in refrigeration cycles, as defined by R-134a refrigerant properties.

In a refrigeration system, as the refrigerant moves through the condenser, it loses heat and transitions from a gaseous state to a liquid state. The pressure of R-134a is correlated to its saturation temperature. When sub-cooling occurs—meaning that the refrigerant is cooled below its saturation temperature at a given pressure—the pressure remains relatively stable unless the temperature is significantly changed.

For R-134a, at typical operating conditions, the pressure corresponding to a saturation temperature around the range of 87 PSIG would suggest a certain temperature. By sub-cooling the vapor by 20°F, you are effectively lowering the temperature of the refrigerant as it exits the condenser. This sub-cooling does not drastically change the overall pressure but maintains it within a specific range characteristic of R-134a under typical operating conditions.

Therefore, based on industry standards and refrigerant properties, it is reasonable to conclude that the approximate pressure of R-134a vapor leaving the condenser, particularly after accounting for the sub-c