Why is the water draining and filling at the same time?

The water inlet valve on your washing machine is used to fill the tub with cold, warm or hot water for the wash and rinse cycles. The valve is operated by electric solenoids that are controlled by the timer or electronic control board and the water level control/water level selector switch or pressure switch. If your washer continues to fill during a drain cycle, the water inlet valve could be at fault. To verify that the valve is at fault, unplug the washer when the symptom occurs. If the washer continues to fill, then the inlet valve is defective. If the washer stops filling, then the problem is related to the electrical circuit that controls the valve.

The water level switch is a pressure activated switch that is used to determine the correct water level in the tub. This part is normally located behind the control panel and will have a hose or air dome tube that connects it to the tub. On washers that use an electronic control, this switch may be located at the sump area below the tub. As the water fills in the tub it will compress the air in the tube and push against a diaphragm inside the switch. The switch will control the water inlet valve and turn the valve off at the correct water level. If the tube has a leak, not enough pressure may be created to activate the switch and the washer may overfill. If the switch is defective it may also cause the machine to overfill. To determine if the switch is bad, you should first eliminate the air dome hose as a problem. Look for signs of cracks or worn areas on the hose. Remove the hose and submerge in water. Seal one end and blow air into the other end and look for bubbles. Check for an obstruction in the hose as well. If the air dome hose appears to be ok, then the water level switch may be defective.