You need to know the pump information before you can hook it up.

Is the pump wired for 240V and the pressure switch for only 120V? What do you want to do? Have your pump run at 240V or 120V? Your description is confusing.

The pressure switch only needs to open one leg of the 240 V to control the pump.

The depth to the pump, the distance from the house to the well and the HP (or amperage draw) of the pump are all important considerations. The #12 is rather small for the typical water well submersible pump installation.

Is there really 12/3 running to the pump? Most well pumps that I've worked with only require 2 conductors, and run at 240V (and frequently require heavier wiring). The pressure switch would also need to handle 240V (and the current required to run the pump). How do you know that the switch is set up for 120V?

well is 230ft, 1hp pump, 90ft rom house. 7amp on control switch provide from well diggers. i guess i can take a close look at presure switch but only two conections for line voltage (square d). so i'm thinking one leg with neutral to preasure swith, wire nut 2nd leg (red)upto control box. blk L1,wt L2, red (2nd leg to r).

sorry it takes time to reply, out in the stick off the grid. no internet until hardware runs. thanks or the replys

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At 320' for your feed you would need to upsize the wire by 2 sizes, so I would suggest 10/2 running at 240V. Two connections for line voltage labelled L1 and L2 means 240V.

Still need to confirm pump specs. Is it a two wire or three wire pump? Is it 120 or 240 volts?

Why would it be a 3 wire pump? It's either 120V or 240V, but not both at the same time, like a stove or dryer.

The 3-wire submersible pumps have a control box mounted above ground level. The 3-wire is more efficient in electricity use and has higher starting torque. Costs more to buy and install. But the supply to the control box is just the two conductors for 240 volts plus the equipment grounding conductor. The original poster seems slow to offer requested information or to clarify exactly what is meant by 12-3. I quickly stop trying to help those cases.

So, 2 wire 240V feed to the the control box, and from the box to the pump is a 3 wire feed? Busdriver, can you explain how that works.

Yes three wire feed to the pump. Since the OP has said the pump feed is 12/3 that is why I am trying to clarify what he has.
In order for a single phase motor to start there is a second winding called the start winding that initiates spinning. It is only used to start the motor spinning then is switched off as the motor reaches speed. It also determines which direction the motor spins. A two wire motor has the capacitor and switching built into the motor. A three wire motor brings that connection out to a control box where the capacitor and switch are located.

Thank you, joed. Now I understand.