Display powers on but machine will not start extraction or pump when Start/Run button is pressed.

Safety: Disconnect power before accessing switches or the control board.

• Check user settings: Confirm the machine is not in a setup or priming mode that prevents normal operation. Reset the machine by turning it off for 30 seconds and back on.
• Inspect Start/Run switch: Remove the control panel cover. Test the Start/Run pushbutton with a multimeter for continuity when pressed. If intermittent or open, replace the switch.
• Solution tank lid interlock: Many Prochem units have a lid or safety interlock. Locate the lid switch near the solution tank hinge. Bypass temporarily for testing by joining the two switch wires with an insulated jumper (only for diagnosis). If the machine starts, replace the lid interlock switch.
• Waste tank float switch: Remove the waste tank and locate the float switch assembly. Check that the float moves freely and is not stuck in the “full” position. Test the switch continuity while moving the float. Replace the float switch if it remains open when the tank is empty.
• Control PCB start relay: If all switches test good, inspect the control PCB for a start relay (often labeled PUMP or VAC). Look for burn marks or cracked solder joints. If the relay does not click when Start is pressed and coil voltage is present, replace the control PCB or have the relay professionally replaced.