When diagnosing a walk-in cooler with heavy ice build-up, the technician suspects?

When a technician diagnoses a walk-in cooler with heavy ice build-up, the suspicion that the evaporator is starved due to a partial loss of refrigerant charge is particularly relevant. In the case of insufficient refrigerant, the evaporator coil does not receive the adequate amount of refrigerant needed for proper heat exchange. This can lead to low temperatures on parts of the evaporator, causing moisture in the air to freeze and accumulate as ice rather than being adequately evaporated.

The starved condition results in an imbalance in the refrigeration cycle, which makes it difficult for the system to maintain appropriate operating temperatures. The evaporator should be cooling the air within the cooler to a setpoint, but with insufficient refrigerant, it cannot achieve this, leading to the observed ice build-up. This situation often occurs because of slow leaks in the system or issues with refrigerant management. Proper diagnostics might involve checking the refrigerant levels and inspecting the system for any signs of leaks or other issues that could contribute to the refrigerant loss.

Other choices may involve valid scenarios, but they do not directly address the specific symptoms of heavy ice build-up as thoroughly. For instance, the evaporator being flooded due to an overcharge of refrigerant would typically create a different set of