APC Smart-UPS RT 3000VA Online-UPS Fan issue / replacement

[FabianLPHD]

Hey there,

maybe someone know an easy fix to replace the stock fan with a silent fan.
The stock fan has only positiv and negativ 24V, so it's voltage controlled.
I tried a noctua nf-a14 industrialppc-24v-3000 but with it the USV has a fan error.
Don't know how the UPS detects the fan... maybe consumption?
APC replied to me that i have to buy a new UPS because it's old and no replacement parts are available anymore.

Thanks in advance and greetings from germany.