My frig is making a loud knocking noise it seems to happen all day on and off and coming from the back of frig plz help

SOURCE: load noise coming from freezer

nothing to do with light bulb - noise is probably fan hitting ice that has built up. to check, remove back panel inside freezer and check for ice build up. melt off with a hairdryer and get back to me if i'm right

SOURCE: loud noise

Check the relay on the side of the compressor. Has a metal clip holding it to the compressor. Check with a volt meter and also check the compressor for voltage. no voltage or low at the compressor replace the relay. You can also take the relay off and shake it. If it makes a rattling sound replace it

SOURCE: frig makes a very loud booming noise/ratteling what is the cause?

The noise is coming from the compressor and is a result of a broken support spring inside the compressor. When the unit shuts down, the inner casing rattles against the outer casing because the spring is not there to keep them apart. The only fix is to replace the compressor but otherwise it is just bothersome.
http://tclaundryrepair.com/home

SOURCE: Load knocking noise

these high efficiency compressors make noise when they are in defrost..you will sometimes hear water running, or tapping noise or even a popping noise. if it happens when its off in defrost.. it will only happen three or four times per day as this is the defrost frequency and nothing can be done without securing the heat exchanger to the suction line ..sometimes these come loose...