There is a strong chance that an electrical fitting is the cause of the smell. Over time and with the help of heat the plastic of electrical fittings can start to decompose - ooze a green liquid and give off a strong ammonia / fishy smell.
Have a good sniff at all the plugs sockets and lamp holders in the room. A poor connection at the back of a wall socket can produce a lot of heat and accelerate decomposition.
My guess is that it's the wall socket you have the fridge plugged into - only smells when the motor runs - same problem with previous fridge.
Good Luck...
March 2016