Hi to you from David The Famous Forry.
This is almost certainly a shortage of gas in your system. This requires specialised equipment and needs to be repaired by a refrigeration trained engineer. Be aware also that this fault is not always repaired by replenishing the gas as there may be a leak to the system, and if the leak is internakl then the appliance is rendered a right off, so be careful how much you wish to risk on repairing the appliance. If it is old I would seriously consider replacement rather than repair. Hope this helps regards XXXXX XXXXX Famous Forry.
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