A container unit's microprocessor-controlled temperature controller is set at -28.9 ° C, appropriate for a frozen cargo of ice cream. In this mode of operation, according to the illustrated temperature controller functional diagrams, what should be the operational status of the unit if the actual box temperature is -18.0 ° C? Illustration GS-RA-035

Illustration GS-RA-035: the U.S. Coast Guard has not released this illustration.

Question

A container unit's microprocessor-controlled temperature controller is set at -28.9 &deg; C, appropriate for a frozen cargo of ice cream. In this mode of operation, according to the illustrated temperature controller functional diagrams, what should be the operational status of the unit if the actual box temperature is -18.0 &deg; C? Illustration GS-RA-035

Illustration GS-RA-035: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option A: cooling mode. When actual box temperature (-18.0 °C) is significantly higher than the micro-processor setpoint (-28.9 °C) for frozen cargo like ice cream, the refrigeration unit must actively remove heat, placing the system into full cooling mode to achieve required box temperature.