The age of a Whirlpool refrigerator can be determined by locating the model and serial number tag, which includes a date code. The date code is the third to the last digit in the model number series. That letter corresponds to a list that reveals the date of manufacture.
The code list is found at ApplianceAid.com. Each letter represents two years, so the refrigerator was manufactured in one or the other. ApplianceAid.com also provides instructions on how to locate the model and serial number tag on the appliance. On a Whirlpool refrigerator, the tag is usually on the inside wall.