If the fins on the evaporator become blocked, what effect does it have on the suction vapor?

When the fins on the evaporator become blocked, this impedes the airflow necessary for effective heat exchange. The evaporator's primary function is to absorb heat from the surrounding environment, which turns the refrigerant inside the evaporator into vapor.

As airflow is restricted due to the blockage of the fins, the evaporator cannot perform efficiently. This inefficiency means that the refrigerant does not absorb sufficient heat, which leads to a lower rate of heat transfer. Consequently, the pressure within the evaporator begins to drop because the refrigerant struggles to vaporize properly under these conditions.

Furthermore, since vaporization is also a process that requires heat, the temperature of the refrigerant will also decrease in tandem with the drop in pressure. This happens because the vapor is not receiving enough energy from the environment to maintain an adequate temperature, resulting in a drop in both pressure and temperature of the suction vapor.

Thus, the scenario described fits the answer where both the pressure and temperature fall, aligning with the understanding of how evaporator performance is impacted by airflow restrictions.