Re: Dessalator Duo 60
referring back to your diagram, If there is voltage between the points A and B on the solenoid then I believe that would indicate that the solenoid is open rather than closed, meaning there is no electrical connection between points A and B. When the solenoid is energized and it's contact is closed, and A and B should have little or no voltage across them.
Before you do anything below make sure you have the unit turned off/depowered so you don't cause an arc while disconnecting wires.
It appears the blue and the brown control wires are the power to the coil in the solenoid which when energized closes the contact inside the solenoid. I would disconnect one of the blue or brown wires and check to see if you have continuity between the blue wire and brown wire when you are calling for the motor to run. This will test the switch. If you have continuity and the blue wire has 24V between it and point A then the control switch is working correctly.
You can test the solenoid by disconnecting B terminal black wire and then calling for the the motor to start. This should close the contact in the solenoid. There should be continuity between points A and B on the solenoid.
The points C and B on the motor should have voltage across them when the motor is energized to run, but no voltage when it is not running. This will tell you if the motor is getting power.
Hope this helps, John
Vent de Soleil SM 037