You've probably been at home on a quiet night when sudden loud thumping sounds begin, and every horror movie you've ever seen flashes through your mind. Upon investigating, you may find it's the fridge. But you don't need to brace yourself for a "Ghostbusters!" moment with finding a demon in your fridge. That thumping sound is to be expected from time to time.
When Thumping Sounds Abound
Apparently, the service technicians at GE have had a lot of calls about noises customers might hear. If you've ever wondered about your GE Profile refrigerator motor noises, the handy list of "normal sounds and noises a refrigerator makes" is delightful reading. Soon, you'll know about the woofing, clicking, gurgling, howling, humming, clicking and clunking sounds that belong in the life of any fridge.
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Usually, a knocking or thumping while the fridge is running tends to be when refrigerant is circulating in the cooling system, and it's typical. If, however, you've turned off the fridge and it starts thumping then, you may have issues with the compressor. Sometimes, the springs in the fridge housing that accommodate the compressor's movements can wear out, causing the compressor or its fan to bonk the fridge wall as the fridge powers down, hence the noise.
If the thumping is indeed happening upon powering down the fridge, then it's a concern but not an urgent one. If the thumping happens while running, and it's only an infrequent thing, such as with coolant being circulated periodically, then that's not a concern either. However, if the thumping noise becomes regular and grows louder, it may be that a fan or something has loosened and is banging inside the unit, and you may want to call a service technician.
Other Noises of Note
LG has a terrific resource on its website for troubleshooting refrigerators. The site shows you a diagram, and you can play the noises associated with each description. They're all "normal" noises you can expect even the most expensive fridges to make — like the clicking and thumping an LG refrigerator will make every 4 to 12 hours as part of its auto-defrost cycling. In that case, the housing of the fridge expands and contracts during the process, hence the creepy noises.
Of the "normal" sounds you can listen to for comparison, LG lists clicking, rattling, whooshing, gurgling, popping, sizzling, dripping and pulsating. One sound of concern, it says, is the "popping and tapping" that seems a bit like shuddering and thumping. It's a normal sound for up to an hour at a time, but it's abnormal if it can be heard from another room by someone with normal hearing.
Just in Case: Maintenance Tips
Most thumping noises have something to do with the compressor or coolant, so if it's something you've been hearing more of lately, maybe it's a good idea to investigate. Make sure you've got the fridge far enough out from the walls (between 1 inch to 5 inches, depending on make and model) so air can circulate properly, and the fridge isn't working too hard.
Also, there may be some dust and debris clogging up the works. Vacuum and clean the toe kicks and get rid of dust around or behind the fridge, as well as any collecting on the condenser coils. Of course, unplugging the fridge is a good idea for a moment if you plan to wipe down the back of the fridge and clean the coils.