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Hi. I'm Smitty and I will be assisting you with your problem.
What is happening is there is frost building up at the back of your freezer compartment on the evaporator coils. the automatic defrost system is what keeps this from happening.
The noise you hear is the evaporator fan hitting the ice. By opening the door you activate the light switch which turns on the light and also stops the fan motor. If you leave the door open long enough the ice melts and the fan then clears it for a period of time.
What you need to do is take everything out of the freezer and remove the panel at the back of the freezer compartment. There are two round caps with the mounting screws behind them. One on either side in the middle. pop them out with a small screwdriver or butter knife and undo the screws. The panel will come off. Use a hair dryer to melt the ice and then replace the defrost timer (also behind the panel). It is part #16-5 in the drawing linked to below.
Let me know if you require additional information.