Defrost

Defrosting (or thawing) is the melting of an object or bringing a device's temperature above the freezing point to remove ice.

A defrosting procedure is generally performed periodically on refrigerators and freezers to maintain their operating efficiency. Over time, as the door is opened and closed, letting in new air, water vapour from the air condenses on the cooling elements within the cabinet.

The resulting ice inhibits heat transfer out of the cabinet increasing running costs. Furthermore, as the ice builds up it takes increasing space from within the cabinet - reducing the space available for food storage. Defrosting the unit is achieved by:-

The process may be sped up by mechanical removal of ice, or the introduction of gentle heat into the cabinet. Placing a pan of hot water in the cabinet and closing it is an effective method. Using a fan to blow in room temperature air will also greatly speed up the melting process as well as help to evaporate the damp surfaces. Note that the fastest manual way is to use a vacuum cleaner: simply insert the hose into the exhaust port (nearly all are designed for this), and use the wand to blow on the coils; this method is much faster than any other.

Any mechanical removal of ice should be done gently so that the equipment is not damaged.

It is generally recommended that defrosting should be done annually.

Many newer units employ automatic defrosting (often called "frost-free" or "no frost") and do not require manual defrosting in normal use. Although, in some cases, users of Frost Free fridge/freezers have noted ice blocking the vent that allows air into the refrigerator compartment. All refrigerators and/or freezers whether or not frost free, should be defrosted at least every 6 months (or more if you live in humid conditions or if the door is opened excessively). Frost Free units should be defrosted every year, as frost can form on the evaporator covers, which can look unsightly and degrades freezing performance, sometimes to the point of the freezer thawing out due to degradation of defrosting. This can happen when the defrost timer is not set up correctly/malfunctioning or if the heater units or temperature sensors are malfunctioning.

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Wikipedia