The BOB input names are relevant especially when you are asking basic questions.
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I believe you are using two 12V fans in series so that you can power them from a 24V supply now have a look at the drawing re the buzzer and the relay coil and see if you can work that out. (I am not trying to be difficult but you have to fully understand the reason) clue is you are halving the voltage with the fans.:friendly_wink:.
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The purpose of the override switch is simply to provide a path to ground to energise the relay in the absence of a limit being tripped ie opened.