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While troubleshooting a home appliance, I found something odd: a 120V AC refrigerator fan stopped spinning despite being connected to 120V AC voltage (verified with my multimeter) inside the refrigerator. But when I hard-wired the fan to a 120V household circuit, the fan runs fine.

I checked the usual culprits (e.g. shorts, corroded connectors, mechanical obstructions) and everything looked OK. Just to verify, I mounted the hard-wired fan inside the appliance and it ran fine. Then I switched back to the refrigerator's connectors and it wouldn't run, and I re-verified 120V AC across its connectors.

My assumption is that the appliance's controller board (or some other upstream electrical component) failed and caused this problem.

What could cause this behavior? My naive understanding was that if the voltage is present, then current will flow. Could the upstream electronics be doing something that prevents current from flowing (at least enough current to overcome the friction of the fan motor) but still shows the 120V AC voltage difference?

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  • \$\begingroup\$ Could be something upstream limiting the current to the fan. \$\endgroup\$
    – earl
    Commented Nov 3, 2023 at 20:07
  • \$\begingroup\$ Yep, that's exactly what I think is happening here. But wondering exactly how that works, given Ohm's law? \$\endgroup\$
    – Justin Grant
    Commented Nov 3, 2023 at 20:09
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    \$\begingroup\$ Multimeters draw next to zero current when measuring a voltage across two contacts; that's why your able to measure the 120V. But when you connect a more significant load like a fan, it will draw much more current from those contacts. \$\endgroup\$
    – earl
    Commented Nov 3, 2023 at 20:12
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    \$\begingroup\$ if the voltage is present, then current will flow The power connection must be able to provide the current required, too. \$\endgroup\$
    – MiNiMe
    Commented Nov 3, 2023 at 20:12
  • \$\begingroup\$ I'd try replacing the fan. Old fans tend to get gunked up, and are harder to get spinning from rest. Your fridge isn't able to provide enough current to fan. Your wall outlet is. \$\endgroup\$
    – earl
    Commented Nov 3, 2023 at 20:14

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