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Where is the pressostat in the washing machine?

The pressostat in the washing machine is broken: what to do

In this article we will talk about the pressostat of the washing machine. a device that converts the change in pressure of a liquid or gas into electrical signals. In “washing machines” pressostat regulates the water level in the drum. But sometimes the relay fails, begins to glitch and give false data to the control module, provoking serious problems.

These sensors are used in automatic devices where it is necessary to control and adjust the water or air supply (compressors, washing machines and dishwashers).

The article is relevant for automatic washing machines of foreign and domestic production: AEG, Ardo, Beko, Bosch Maxx, DAEWOO, Candy, Gorenje, Hansa, Hotpoint Ariston, Electrolux, Indesit Wisl, LG, Miele, Samsung, Siemens, Vestel, Whirlpool, Zanussi, Atlant, Vyatka and others.

In a washing machine is broken pressostat: what to do

The automatic washing machine is controlled by an electronic unit, which responds to signals from control devices, the main one being the pressostat. It is a multifunctional sensor that is responsible for filling the washing tank with water to a certain level, timely switching on the heating, pumping liquid. Understanding the principle of operation of the device, the ability to make diagnostics yourself will help save the family budget from unnecessary costs.

  • Appointment of the pressostat
  • The principle of operation and types
  • Signs of level switch failure
  • Independent diagnostics of the pressure indicator
  • Can I adjust the settings myself?
  • Do I have to do it myself?
  • Washing machines catalog with reviews

Setting the water level sensor

The pressostat is set to the required amount of liquid by means of two adjusting screws, one of which (central) is used to set the contact connection moment and the other (peripheral) is used to set the contact breakage moment. There can be several contact groups or sensors, depending on the modes of operation and the model of the washing machine. Different washing programs can also use different amounts of liquid in the washing machine, e.g. economy or gentle washing, which requires half of the tank to be filled.

Exact adjustment of the alarm is performed by specialists at the factory, and the position of the adjustment screws is fixed with paint or varnish. Changing their position is not recommended, because unbalancing the setting will cause violations in the well-established washing program. To set up the unit correctly yourself, you need to know how much liquid the machine requires at each stage of all washing modes, and in accordance with this set the moments of switching on and off the contact groups. For example, the pressostat of a Bosch washing machine has three contact groups, set for full mode, economy mode and tank overflow.

See also. Washing machine jumps when spinning

Where and How Much to Buy a New Part?

You can purchase a new water level sensor in a specialized service center or store, or order one on the internet. Sometimes the part is available at private masters engaged in repair of washing machines.

However, very often they sell used pressostats that have been removed from other appliances. Such a sensor can work for several years or a few days. It has no warranty.

Before making a purchase at the store, you need to make sure that the new sensor is exactly the same type and name as the previous one. It must match the make and model of your washing machine.

This parameter directly affects the price of the sensor and varies from 900 to 2000

The newer and more expensive the washing machine, the higher the price of all the components.

When buying a sensor, you need to get a receipt from the seller. If it is defective, it must be replaced at the point of sale.

About the product

The simplest name for the product is “washing machine water level sensor,” which also describes its main function. Each machine has a pressostat, whose task is to determine the presence of water in the inner tank and the level of its filling. If this sensor is missing, the controller will not be able to determine when it is safe to start the laundry.

To determine where the pressostat is located inside the washing machine, look closely at the round plastic device to which the wires and tubes are connected to the tank. Characterized by its small size and uncomplicated attachment, so that it can easily be disconnected and connected on its own. The water level sensor includes the following components:

  • Sensors. Measures the water level by means of an integrated diaphragm, which takes on a column of liquid. The pressure of the latter is converted into kilohertz, through which the user is informed of the degree of filling of the inner chamber of the washing machine.
  • The compression chamber is located at the junction of the pressostat and the water inlet hose. Must be regularly maintained, otherwise it will quickly become clogged with debris and the contents of the incoming liquid. If it gets dirty, the water level measurement becomes inaccurate, and later the hose stops pumping it out.
  • A diaphragm or membrane that slides under pressure and clicks on a core switch.
  • Technical components. printed circuit board and coil. They are responsible for maintaining the functionality of all parts of the pressostat, as well as converting the signals coming from the diaphragm and turning them into an accurate value.
  • Ferrite core. As an alternative a magnet is possible.
  • Adjustment screw to allow adjustment of the pressostat.
  • The springs that support the adjusting screw and return it to its original position.
  • The enclosure encloses all components of the water level gauge, protecting them from damage during operation.

As can be seen from the description, the component parts of the pressostat are quite simple and not highly reliable, which requires careful handling of the device during its installation, disassembly and maintenance.


How to adjust the pressostat in the washing machine “Indesit”? The pressostat must first be accessible. As a rule, it is located on the side wall of the washing machine, closer to its top. Do this in this order, this is the diagram:

  • Unscrew the two rear bolts that hold the top cover, remove it.
  • Unscrew level sensor. Most often it is attached to one or two bolts.
  • Disconnect electrical plugs and tubing from indicator. The tube is secured with a clamp, so you will have to unscrew the clamp. Disconnecting the wires is not too difficult.
  • Inspect the pressostat to make sure it is intact. Check the tube for damage as well. It must not be damaged or clogged. Replace a damaged or clogged tube.
  • Inspect indicator pins. If they are dirty, clean them up.
  • Check the pressostat. Take a 10 centimeter piece of tube of the same diameter as you use on the gauge all the time.
  • Hang the tube at one end of the indicator inlet fitting and blow on the other end. If the pressostat is functioning, you can hear the characteristic clicks.

Important! You can also use a multimeter: as the air pressure increases, the conductivity changes.

The device of the washing machine pressure switch

The device of the washing machine pressostat looks like a disk with an air chamber located inside, equipped with wires and a tube, the other end of which is in the tank of the washing machine.

The incoming liquid increases the air pressure both in the tube and in the chamber of the pressostat.

pressostat, washing, machine

This raises the rod, which presses the contact plate under the spring. This happens until a certain amount of liquid is reached.

Then the electric circuit of the inlet lamellae of the relay closes due to the spring plate switching to the upper position.

Diagnosing Washing Machine Pressure Switch Problems

When the water is drained, the pressure decreases and the rod crawls down, which causes the relay to switch already down, with an interruption of the electrical circuit. The module already further transmits information and commands to the pump, heater, intake valve and motor.

Typical defects

Failure of water level sensor is most often indicated by a malfunction:

  • Washing mode begins before there is water in the machine. When starting a wash cycle, the control module turns on the heating element to heat water. Without water in the tank the heating element overheats and burns out.
  • Too little or too much water to wash. Control module may not close inlet valve due to a faulty pressostat. This causes the machine to leak and flood the room.
  • After spin cycle the laundry is still wet. Water is not completely drained from the tank after washing mode.
  • Water does not leave the tank at the end of the wash cycle and the machine does not open the door. Pressostat does not signal to the control module when water is present and the module does not turn on the drain pump.
  • Washing machine does not work and shows an error code on the display. This is only possible in machines with self-diagnosis. Decipher the error code to find the broken part.

Sensor Test Guide

Before you try to check the pressostat on the washing machine Bosch Maxx 4 (or Samsung) with a tester or improvised means, you should weigh the validity of this action. If the washing machine is under warranty, unauthorized interference in the unit operation will be a reason to refuse warranty service from the seller or the manufacturer.

Sequence of Operations:

pressostat, washing, machine
  • Remove the power cord from the socket.
  • Dismantle the top panel by removing the two small screws that are on the back wall side and sliding the panel back and up.
  • Locate the sensor cantilevered to one of the housing walls.
  • Remove the connector, release the fastener (screw), pull the sensor hanging on a tube out of the machine.
  • Using pliers, open the clamp on the supply tube and remove the unit.

Before you check the adjustment of the device using tools, you can assess the overall performance of the sensor. For this you need a piece of tube identical to the rubber tube of the relay. After taking the device out of the machine, you should connect it to a short tube, blow into it hard and see if the relay inside the device clicks in response to a change in pressure. If not, the sensor is defective.



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