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4.4 Defrosting
During cooling, the air releases moisture that accumulates gradually between the evaporator fins until freeze and
block the passage of air which progressively reducing the efficiency of the system and subsequently causing
damage.
For this reason, regularly it does a defrost cycle in order to melt the ice accumulated and drain externally water.
The control unit manages autonomously and periodically the beginning and the end of the defrosts.
The type of defrosting change from the use of the unit:
-
Air defrost
It is the simplest solution and consists in practice in a stop of the unit in order to allow to melt accumulated
ice while maintaining active fan. It is available on R134a units and recommended only if the vehicle is
intended exclusively for the carriage of products at temperatures above 5°C.
-
Hot gas defrost (Optional for R134a unit)
It’s a much more effective solution and uses the heat generated by the compression of the refrigerant gas,
which is deflected by a solenoid valve directly into the evaporator ensuring the melting of accumulated ice in
the evaporator. It’s present on the units dedicated to the transport of frozen products and is generally
recommended on units intended for the carriage of goods at temperatures below +5°C.
-
Reverse defrost cycle (Optional)
It is a very effective solution, is accomplished by reversing the direction of the refrigerant. For condensing and
evaporating that are exchanged thermal functions through a special valve called "4-way valve".
Advice
The efficiency of the defrost is inextricably linked to the accuracy of drain water line.
The steepness of the discharge is such as to ensure the smooth flow of the drain water
Periodically check the outflow of water from the drain hose.
Minimize opening the cell and turn the unit off during loading and unloading of the goods in order to
minimize the introduction of external moisture into the cell
In case of intensive use of the unit check regularly the accumulation of ice in the evaporator and
periodically run a stop in order to ensure the complete melting of all the ice.
4.5 Heating function (Optional)
If the unit operates in extremely variable climatic conditions, in certain circumstances and periods of the year in
order to keep the temperature of the product within the desired range, it may be required heating of the cell as an
alternative to the cooling.
For example of the transport of leafy vegetables or flowers for which must be guaranteed a temperature comprised
between 5 and 10 ° C, when externally we temperatures significantly below zero.
From the technical point of view the heating exploits the same principles used for hot gas defrosting) with in
addition the activation of the evaporator fans.
In the units with air defrost it is provided a further option for heating, through the use of electrical resistors, active
only during the road mode operation.
4.6 Multi-temperature operation (Optional)
It allows the management of two compartments with different temperature. The unit is equipped with multiple
evaporators and a dedicated control unit, which manages the two temperatures independently of each other.
The heating function is also included in the logic of operation.
