Air conditioner and refregirator working on same principle. It sucks the hot air and releases the cool air to the enclosure. Air conditioner is working in high capacity to cool the room to the desired temperature, But refregirator capacity is linited to the enclosed volume of refregirator. If the fridge is open, cool air will spread to the room and room temperature will come down slightly. But the load on refregirator will increase and the compressor coils may burn out. So it is not advisable to cool the room by opening the doors of refregirator.