Miele Dishwasher

Model G638

This dishwasher was not working, the initial test indicated that the dishwasher was not filling. Putting water into the dishwasher with a bucket and testing showed that the wash pump operates, the heating element works and also the drain pump works, so the only problem was the filling.

This dishwasher had a “no burst hose/valve” with the valve at the tap and low pressure hose to the dishwasher with the two wires to the valve. Some people call the anti-flood hoses but I have only had a couple of hose burst creating a flood, but lots of slow leaks which can create just as many problems. To remove the hose/valve for testing required the dishwasher to be removed from the cupboard and half remove a side panel. Connecting the hose to a tap and powering the valve using suicide leads produced a good flow of water. This blow the idea that the valve was faulty, the most likely cause and another fault had to be found. Since it was that time of the day to go home (beer o'clock) the dishwasher was loaded and brought back to the workshop.

Back at the workshop the side panel was completely removed and the hose/valve was reconnected. Again no water flow. The water enters a complex channels in translucent plastic with a solenoid and a flow meter. It had 5 hose connections including the water inlet. Since it would be very to measure the voltage at the miniature plug and socket, I choose to remove the door front panel. The owners through that the dishwasher looked better if the if the front panel matched the rest of the cupboards so it had a heavy wooden panel on it making it very heavy. Looks before ease of service! Inside was a circuit diagram, this was written in German, with many columns in different languages including English. This helped locate the wires to the valve, resistance measurement from the PVB plug to the valves showed the wires through the flexing of the door was not broken, a common problem with dishwashers, particularly with the higher current carrying wires. This proved the wires and the coil in the valves where OK. Next the dishwasher was powered up and 240v was present on the water valve connectors, the Triac in the PCB was OK. Great care is needed in testing live equipment with covers removed!

Running out of ideas, next removed the inlet hose from the inlet chambers and tested again, this time water flowed onto the floor. Reconnecting the hose again the dishwasher was filling, as the water can be seen flowing through the translucent plastic inlet chambers. It must have a “air lock” in the chambers. Tested and drained the water out several times without any fault. The machine was returned and tested in the kitchen without any problems. Frustrations of fixing dishwashers!