Which mode of operation is expected to cause spikes in Discharge Air Temperature?

The correct choice regarding the mode of operation expected to cause spikes in Discharge Air Temperature is the defrost mode. In a refrigeration system, the defrost mode is activated to remove frost or ice buildup on the evaporator coil. During this process, the system temporarily shifts its operation, typically by reversing the refrigeration cycle or supplying hot gas to melt the ice. As a result, there are rapid changes in the temperature of the air being discharged since the system is transitioning from cooling to a heating state to effectively defrost the coil.

The defrost mode leads to elevated temperatures in the discharge air because the system is no longer focused on cooling but rather heating to eliminate frost. This behavior is typically characterized by unpredictable temperature spikes, which differ significantly from steady-state operations in cooling or heating modes.

In contrast, the other modes such as cool mode, heat mode, and modulated cool mode operate under relatively stable conditions designed to maintain a consistent air temperature, which would not lead to the same level of fluctuation as seen in the defrost mode.