[Sally Larson]

Every time my Kitchenaid refrigerator (purchased in April 1998) stops running, it makes a loud "clunk" sound that sounds like it is coming from the back of the unit near the bottom. Sometimes the "clunk" is very loud and sometimes it is softer but it always makes a "clunk" sound when it stops running; otherwise, the unit seems to be functioning just fine in all other respects. Any ideas?

[denman]

Here is a link that should answer your question and give some other things to check.
refrigerator problems and solutions, not cold enough, frost free repair information
Take a look at #24

Sorry to be the bearer of bad news

[kayakcrzy]

That clunk is your compressor. It is the internal motor mounts inside. It could run for another 20 years, just clunking away. If you replace it, it would make a good garage refrigerator. Tom ApplianceEducator.com