Knocking noise occurs about 20 seconds after compressor starts. Sounds like someone knocking on a wood door. It last about 8-12 knocks and then stops. It does not occur everytime the compressor starts but more times than not. There is no water hooked up and the ice maker is turned off.

https://www.youtube.com/watch?v=sLR2vKxgwbM

A freezer compressor is what pumps chilled Freon -- or another cooling agent -- through coils that line the freezer compartment. ... The cooling agent inside the compressor is sensitive to being moved around, which can cause knocking noises. Also, loose components can cause knocking sounds.

This is the first sign of the compressor going out. You will either need to replace the compressor or purchase a new unit.

could be one of the doors in the heater box

Pull the fridge away from the wall and inspect the compressor. Your description sounds like the compressor is hitting something. It is rubber mounted and usually can be pushed away from whatever it is hitting.You do not want to jamb something to stop the noise, as the compressor needs to move freely. Many compressors shake during start up and shutdown, and this is considered normal. Abnormal if the compressor hits something during this movement.

it could be the compressor

ProbabyTry to Change Rubber Base Groumet for Compressor motor and there is nothing with freon

Kindly inform me When Solved

Good Luck

sounds like the compressor vibration dampers are wearing out. the dampers are the rubber washers that seperate the compressor from the chassis of the fridge. when they start to deteriorate, and the compressor kicks on, it will bounce against something in the chassis, causing a knocking noise.

Check the compressor mounts. They are usually springs mounted with rubber. If they are two loose the compessor wil hit some other metal part when starting up. Shakle it and see what it is hitting. Ajust accordingly. 

I also have a new Whirlpool Gold fridge (bottom freezer with French doors) and it was making a knocking sound. The knocking sound would start when the fridge kicks in and starts running to cool, and would last for about a minute or less and be a slow knock.
I called Whirpool customer service since it is new and on warranty. They sent out a technician and he said the knocking is from gas/air built up in the copper tubing for the freezer because the copper tubing is too cold, and when the fridge first turns on it forces the air through, making the knocking sound.
His "fix" was to adjust the copper tubing so that it is closer to the heat of the motor/compressor and heat of another copper line so that the cooler line stays warm so the air/gas doesn't build up. His fix worked slightly, but the fridge is still knocking, just not as bad and not as long - it knocks fast for about 5 to 10 seconds instead of a minute.
Going to call customer service again soon and see where to go from here.

the motor could be on the way out. Put your hand (carefully) on the motor (back of the refridgerator), if it is too hot to touch then the motor is burning out and will need to be replaced.