A relay is remotely mounted electricity operated switch. When you send power to relay you energized the coil closing the contact on the load side sending higher electric energy. Each relay needs ground to complete activation. Both have load circuits but only the left has activation ground. The right has incomplete activation circuit. If it not shown it does not exist.@GoToGuy
Was it my hand drawn diagram you were referring?
My understanding was OP wanted auxiliary fans ONLY when a/c was activated at idle, then being able to turn them off at speed-running the switches in series would allow that.
I could have drawn the diagram better, the input for the toggle switch would just be T’ed off of the a/c switch, or compressor clutch, or pressure switch etc… also, terminal 86 is fed switched power on both relays. People keep saying there’s no ground so maybe it isn’t my diagram
Electricity is a little like water, always wanting to find the shortest route to ground, and a little math , Ohms law, you can make it all balance.