I take it that the compressor must be constantly running? otherwise it wouldn't get cold!
yet you say there is no sound!!
Can I understand that it is not near or backed onto any radiators?
Where is the appliance located! if its in a too cold or too warm a location then it might be being fooled by the ambient temp!
Otherwise sounds like the thermostat has faulted! OR the door seals are split or not matching upto the body!
It will NOT be a lack of gas issue if it's getting cold!
Steerpike, May 2008