What is the state of the refrigerant as it leaves the evaporator?

As the refrigerant leaves the evaporator, it is in a low-pressure vapor state. This is because the primary function of the evaporator is to absorb heat from the surrounding environment and convert the refrigerant from a liquid state into a vapor. During this process, the refrigerant absorbs heat and undergoes a phase change from liquid to gas, which occurs at low pressure due to the design of the evaporator.

In a typical refrigeration cycle, the evaporator operates at low pressure to allow the refrigerant to boil and absorb heat efficiently. Once the refrigerant has absorbed enough heat, it becomes a low-pressure vapor, which is then sent to the compressor to be compressed into a high-pressure gas. This fundamental principle of thermodynamics underlies the operation of refrigeration systems, making the low-pressure vapor stage critical in the heat exchange process.

Understanding this phase change is essential for diagnosing and servicing HVAC systems, as it plays a significant role in system efficiency and performance.