Why replacing only fan blades?

[PandaBear]

While troubleshooting some fridge noises I noticed many YouTube videos on replacing only the fan blades. Why would the blades be worn instead of the motor assemblies? Wouldn't they be on the shaft and if they hit something it would have been the shaft being out of balance, and the whole motor assembly needs replacement?

 

[bullwinkle]

Some of them are plastic, they can crack & break off. The whole thing is cheap enough I would replace it all while I'm in there. Sometimes a defrost problem can damage them too.

 

[JHZR2]

Some refrigerators build up ice jams in the coil area where the fans operate. Often the noise is fan blades hitting the ice. If the fan blades wear down... then they need to be replaced. If the fan still spins, while it seems penny wise, pound foolish to keep the motor, perhaps if it's young and easy to get to, it saves cost.

 

[JLTD]

Balance and efficiency. I had a furnace that had (IIRC) a 14-blade fan; one of the blades was broken off and it was imbalanced enough to cause the whole unit to switch off. Once the fan (and only the fan!) was replaced, it had no further problems. Efficiency suffers when the fan blades erode over time.

 

[PandaBear]

Interesting. Thanks for the answers.