I copied and pasted this from a GOOGLE search:
"A popping noise coming from your refrigerator is usually considered normal and is most likely caused by the expansion and contraction of plastic and metal parts inside the fridge due to temperature fluctuations during the cooling cycle, particularly when the defrost heater turns on or off; this is referred to as "thermal expansion" and is nothing to worry about unless the noise is excessively loud or frequent.
"Key points about popping noises from a fridge:
"Normal behavior: Most popping sounds are simply a result of the fridge's natural operation and temperature changes, causing materials to expand and contract slightly.
"When to check: If the popping noise is very loud, happens frequently, or is accompanied by other unusual sounds or malfunctioning, [then] it's a good idea to check the fridge for potential issues.
"Possible reasons for popping noises:
"Defrost cycle: The defrost heater turning on and off can cause ice to melt and re-
freeze quickly, leading to popping sounds.
"Door opening and closing: Rapid temperature changes from opening the door can also cause popping sounds.
"Plastic parts: Plastic components within the fridge can expand and contract with temperature changes, creating popping noises.
"What to do if you're concerned:
"Observe the noise: Pay attention to when the popping occurs, if it's related to the defrost cycle, or if it happens after opening the door.
"Check for ice buildup: If the popping is frequent, [then] check the evaporator coils for excessive ice buildup, which could indicate a defrost issue.
"Consult a professional: If the popping noise is very loud, persistent, or accompanied by other problems like poor cooling, [then] contact a qualified appliance repair technician."
