What happen if you leave the refrigerator door open ?

If you think that the room temperature gets colder when the refrigerator is left open then you are wrong.

The contents of the refrigerator will start to warm up and cause damage

 Formation of Moist

Cooling will also take longer

Compressor might be damaged

Why room become warmer if the refrigerator door opened for a long time ?

When we leave the refrigerator door open for a while, it takes heat from the room surrounding and release back to the room. To cool down the whole room, the compressor will work more and more. Thus it will release it's heat to the atmosphere as well