General

Aurora HF-75S Exhaust Fan Wiring, High and Low Speed Selection

Covers the wiring of the HF-75S exhaust fan for Aurora Fiber Machines, including high and low speed selection and plug connections.

1 min readUpdated Jul 2026
Applies toAuroraTopicGeneral

This article covers the wiring of the HF-75S Exhaust fan for the Aurora Fiber Machines.

For more information on the fan: HF-75S 3 Inch 27 CFM MIXED FLOW INLINE FAN

Main Label

Factory wiring is for the High Speed, 29W, 120V, .50A and 27CFM

HF-75S Main Label

Internal Wiring to the Fan

Typically a Blue wire is used for the Neutral and a Brown is used for the Line. If a Different wire color is used on your plug, double check the wire colors in the junction box on the Fan itself.

Schematic on the back of the cover: Cable is wired on the right, fan wiring is on the left.

Fan junction box cover schematic

High speed wiring is shown below. To change to low speed, move the Brown (Grey), Line wire to the right terminal, LB with the Red wire (Supposed to be brown per the fan junction box cover)

High speed wiring inside fan junction box

Plug Connections to Test if Modifying the Fan Wiring

  • Blue Neutral goes to the Left Pin with the orientation shown
  • Center Pin is no connection
  • Brown/Grey wire goes to the right Pin with the orientation shown
Plug connection orientation

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