Unloading same as loading ,all need close the refrigerant units . The reason is that if the refrigerating unit evaporator has been working state, the front of fan is positive pressure, back is the negative pressure , air-conditioning blowing from the upper part of the compartment, then the lower part of the outside will be quickly sucked into the hot gas, resulting in compartment temperature fast rise, if the refrigeration unit is temporarily shut down, the same pressure inside and outside of the compartment, the speed of external heat into it will be slower accordingly.

Please close the refrigeration units when you load or unload goods.