Consult the manual for your dispenser and look over your soap dispenser's construction. You should have a bottle or reservoir that holds the soap and a dispenser part, which has a valve and tube that pushes the soap up through the head.
Unscrew the bottle from the dispenser top. Fill the bottle with hot water and screw the pump back on. Pump the top a few times to remove any buildup inside. Pour out any remaining water before filling with soap.
Pour in soap recommended by your dispenser manufacturer. The appliance-maker Bradley suggests that soap with a balanced viscosity and pH level is ideal for soap dispensers. Thicker soaps often stick in the dispenser's pump and clog the flow to the head.
Soak your dispenser valve and pump in hot water for 20 to 30 minutes or in a cleaning solution. If it's still clogged, separate all the parts from one another. Soak and clean each piece separately.