Replacing the pressure switch in a dishwasher

pressure switch for dishwasher If the dishwasher starts to work differently than usual, then you shouldn’t turn a blind eye to it. Any breakdown should not be ignored, even if it is something minor at first glance, after some time it can lead to expensive repairs to the dishwasher. Therefore, let's talk about what to do if the pressure switch does not work, and how to generally understand that the water level sensor is broken and requires replacement.

Pressostat: types and principle of operation

The structure of a dishwasher resembles that of a washing machine, and therefore it also has a built-in water level sensor, the second name of which is a pressure switch. The main task that the pressure switch performs in a dishwasher is to monitor the water level in its tank, while the sensor does not come into contact with water. To determine how much water has entered the tank, the pressure switch uses air pressure.

When you add water to the dishwasher, the air pressure in the hose or in a special tank increases. This pressure is transmitted through a tube to a pressure switch, inside of which there is a rubber membrane. The membrane expands under pressure and operates switches that are set to different air pressures, which correspond to different amounts of water in the dishwasher.

The pressure switch can have different devices: mechanical and electronic. A mechanical water level sensor has a relay and a switch in its device; an electronic board is installed instead of a relay in an electronic sensor. Both sensors require replacement if they break down.

For your information! In dishwashers with a flow-through heating element, a paddle-type flow meter is installed instead of a water level sensor.

Signs of a broken water level sensor

pressure switch for dishwasher How can you tell if the water level sensor in your dishwasher is broken? To do this, you need to carefully monitor the water that enters the dishwasher chamber. Symptoms of a malfunction may include the following:

if there is too much water in the machine chamber or, on the contrary, not enough water;
if water is not collected at all;
too much water is poured in and it starts to drain;
The machine has stopped during operation and water is not pumped out.

The causes of failure and malfunction of the water level sensor can be:

wear of the sensor over a long period of operation;
oxidation of sensor contacts;
a defect in the pressure switch elements, for example, a puncture in the tube, as a result of which air escapes and the pressure does not reach the required value, the pressure switch does not work;
pressure tube clogged. Since the pressure in it is very small, then Even detergent, not to mention food residues, can cause a malfunction.

Conclusion! If there is no pressure in the hydraulic circuit, for any of the reasons described above, the dishwasher will not work.

Check and replace algorithm

Before changing the pressure switch itself, it is worth checking its functionality. To do this, you need to provide access to the sensor. In most dishwasher models, including Bosch, Electrolux and Ariston, it is located at the bottom of the dishwasher. We do the following:

disconnect the washing machine from the water supply, sewerage and electrical networks;
turn the dishwasher on its side or upside down; to do this, prepare a place, cover it with a rag so that any remaining water does not fall on the floor.
if your Ariston or Electrolux dishwasher model has a cover on the bottom, then remove it; you may need to unscrew the back panel;
now find the pressure switch from which a tube goes to the pressure reservoir (small plastic box) secured with two bolts;
Using pliers, you need to carefully remove the tube from the tank. And then dismantle the pressure tank itself and check it for blockages;
To check if the sensor is working, you need to blow into the tube and listen. If there is a click, then the sensor is working, otherwise not;
Important! Since the water is constantly moving, the air pressure on the pressure switch membrane changes all the time, which means it would work very often. To avoid this, we set a delay of a couple of seconds, so when you blow into the tube, wait a little.
to check the electrical component of the sensor, you will need a multimeter; if there is a smooth decrease in the resistance to zero, this means that everything is working properly;
If a malfunction is detected, we replace the sensor with a new original one; there is no point in repairing it. In dishwashers of different brands Ariston, Bosch, Miele or others, the pressure switches may differ, buy only suitable spare parts;
To replace, disconnect all sensors, the pressure tube and connect a new unit. Assemble the dishwasher.

So, changing the level sensor in a dishwasher is not difficult if you know how the machine works. If you doubt your abilities, contact a specialist service center. Together with the sensor it is sometimes required replace dishwasher pump, you can also do this yourself, although repairs will cost more.