Temperature controls used on most commercial reach-in coolers primarily sense the temperatures of?

The correct answer is based on the function and design of reach-in coolers in commercial settings. The temperature controls in these coolers are primarily designed to monitor the temperature of the evaporator coil. The evaporator coil is crucial because it is the component that absorbs heat from the interior of the cooler, allowing the refrigerant to cool the air inside the unit. When the temperature of the evaporator coil rises above a certain threshold, the system activates the compressor to circulate the refrigerant and remove heat from the interior, thus maintaining the desired temperature setting.

Monitoring the evaporator coil directly allows for precise control over the cooling process, ensuring that products are kept at safe and optimal temperatures. This approach is essential for food safety and preventing spoilage in commercial refrigeration applications.

In contrast, other components like the condenser unit and the ambient air do not provide accurate readings for the internal temperature management required in these coolers. The compressor unit's role is more about cycling the refrigeration process rather than temperature control. Understanding the significance of the evaporator coil in this context highlights its role in overall refrigeration efficiency and effectiveness in commercial systems.