What symptom might suggest an issue with restricted airflow in the refrigeration unit?

The presence of ice buildup on the coils is indeed a strong indication of restricted airflow in a refrigeration unit. When airflow is restricted, the refrigerant does not circulate properly, leading to a drop in temperature on the coils. As temperatures decrease, moisture in the air can freeze on the coils, resulting in ice accumulation. This buildup can further exacerbate airflow issues, creating a cycle that negatively affects the unit's performance.

In contrast, cooler than normal temperatures may not directly indicate airflow issues, as they could be a result of other factors, such as thermostat settings or environmental temperature changes. Reduced noise levels could suggest that the fan is not operating properly or is not running at all, which would also affect airflow but is not as direct an indicator as ice buildup. Increased energy consumption might indicate that the unit is working harder to maintain desired temperatures, potentially due to inefficiencies, but it does not specifically point to restricted airflow. Therefore, the presence of ice on the coils is a clear symptom of airflow restriction, making it the most relevant choice in identifying potential issues within the refrigeration system.