In many instances the low and high speed coils share an external wire.
How to wire high low switch on a attic fan.
High low common and ground going to the cooler.
The louvers in front of the fan located in the attic open by the wind generated by the fan i e.
Determine the fan switch location.
Here are 3 tips to help.
Install the switch box and switch.
Run a black wire from the low speed post marked on the rocker switch to the marked low speed line on the fan motor and a red wire between the high speed posts on the rocker switch and fan motor.
The line comes from the timer to the common of the three way switch.
Find a live receptacle for the power source.
Use wire nuts to connect the black wire from the 12 2 wire to the black or red wire in the attic fan the white wire to the white wire in the attic fan and the two ground wires.
There should be 4 wires.
I d start by examining your high low switch to see how it works.
If you are trying to switch the speed on the roof mount cooler then you should use a cooler wall switch.
At least some fans that use a high low switch use a 3 way switch.
These louvers are not energized but the aforementioned louvers in the 2nd floor ceiling open via an electrified switch that when energized with electric pulls the louvers open.
The attic fan has 2 speeds.
The process of wiring an attic fan involves the power source and switch location wiring connections to the switch and wiring connections to the fan.
Additionally the low speed coil is typically supplied by a red wire while the high speed coil is fed by a black wire.
The dedicated cooler wall switch have 5 position that can operate the fan on hi and low and fan with pump on hi and low.
Since you have to choose between the speeds using a two speed motor switch it s impossible for both coils to become energized simultaneously.