I'm not a refridgination engineer (probably even spelled it wrong, but hey).
When a gas expands suddenly it loses any heat it may have been carrying. This is because it has done work against the medium it was expanding into, and therefore used its energy.
The basics of a fridge is that it pumps gas round it. The gases warmed by the contents of the fridge are forcibly pumped out through a smaller opening and lose heat when they expand by being released into the larger tubes at the back of the fridge. The same cooled gases are then pumped back through the system.
This is not to be confused with the human body. We gain weight when we expand. Expelling gas does not make us lose the weight. OK all farters out there???