Kenmore Coldspot refrigerator thumps when compressor turns off

I have a Kenmore Coldspot refrigerator model 106.9751713 Serial EF3423274 and the MFG date was 08-96 so it's almost 20 years.

The fridge works fine, still cools, and no noticeable noise. The only thing is, when it turns itself off after reaching the desired temperature, there is a loud thump that last about a split second, similar to a water hammer noise. This has been going on for two weeks now, and it still runs.

I looked up the various diagnosis online about noises and they mentioned clicking, vibrations, squeaking, humming, cracking noises and this doesn't sound like any of that.

While the refrigerator is running, there is no noise, and it doesn't matter if I have the door opened or closed. Also I never hooked up the ice maker and that lever in the ice maker compartment is off, I know what that sounds like.

This is only happening when the fridge shuts off after the cooling is done, a loud thump (or a muffed bang) then nothing. No noise when it starts up, no noise while it's running, only when it turns off.

Any idea what to look for? :confused:

Kenmore Coldspot refrigerator thumps when compressor turns off