My 18 year old Sears refrigerator (freezer on top) pops and clicks.
Then the motor or fan stops with noisy clatter.
Works fine otherwise.
Easy fix or replace?

You can replace the fan motor. It's an easy fix. Some fan motors are hard to get at but once you figure out how to get at the thing - it's an easy fix.

Sounds like your fan motor is going, going and could be gone soon. 18 year old fridge? You sure got your money's worth out of that one!

Get the correct part before you change it out. Call up Sears and get the correct replacement motor first.

Or the clatter could be caused by the fan wobbling and the fan blades hitting against something. Easy to tell once you've opened up the compartment to check out the actual motor itself. Sometimes the fan motors get off balanced resulting in the blades hitting against some of the housing causing the noise.