Owners of automatic washing machines rarely delve into the device of their "assistant", and when a malfunction occurs, they rush to call the master. Often breakdowns occur due to failure of the device, which is called a pressure switch, or a water level sensor. In the washing machine, this is a small but important part, which, fortunately, can be replaced.
Purpose and design
During washing, a set of clean and contaminated water drains, rinses. Each step requires a fluid level set by the manufacturer. Regulates processes by applying a signal to the control controller circuit, pressure switch. Often it is called a "water switch," "pressure sensor."
The task of this part is to determine the amount of fluid in the tank. When executing the program, the sensor “gives a command” to open or close the water supply and pumping valves.
Manufacturers design the device depending on their ideas about what the sensor should be for a particular model. Often the pressure switch looks like a plastic part, to the contacts of which electrical wires are connected. In addition to the relay, a rubber compression tube is connected, the other end connected to the tank of the washing machine.
The figure below shows a generalized diagram of the internal structure of a water pressure sensor.
As the washing machine is filled with water, an excess pressure is created in the air chamber of the tank, which acts on the membrane through the rubber tube through the inlet fitting. The elastic membrane, deforming, moves the rod that closes the groups of contacts of the sensor. Depending on the program, water is supplied or pumped out of the washing machine.
The adjusting screws set the response levels of the relay.
Pressostats have one, two or three groups of contacts - their number depends on the washing program. Some models are configured for different operating modes, depending on the weight of the loaded laundry.
Pressostats of different manufacturers are not interchangeable - for Kandy, for example, a part from Samsung or Indesit will not work. The sensor is replaced with a similar or another one recommended by the manufacturer.
Common causes of pressure switch failure:
- mechanical destruction of the membrane - under the influence of air, it ceases to deform, remaining in one position;
- burning contacts or their thermal deformation - when the rod moves, the signal does not arrive at the controller of the washing machine;
- loss of elasticity or breakage of the spring inside the sensor.
Signs of breakage
The defective state of the relay is determined by the characteristic external signs and violations in the operating mode:
- a lot or, conversely, a little water is collected in the tank compared with previous (successful) washes;
- after washing, liquid remains in the machine;
- water is continuously drawn into the washing tub.
- the machine does not go into rinse mode.
- washed laundry is wet at the end of the spin program.
- washing starts without pre-filling the tank with water.
How to check the pressure switch?
Independently check the serviceability of the pressostat by removing it from the washing machine.
Part removal procedure
- Disconnect the device from the network by unplugging the power cord from the outlet.
- Remove the top cover by first unscrewing the mounting bolts located on the back of the machine and slightly sliding the cover.
- Find a water sensor (usually located on the upper side of the side wall).
- Disconnect the air compression hose by first removing the mounting clamp.
- Without removing the sensor, try to blow the hose. If it is clogged, this is not easy or impossible. In this case, the sensor did not work because it did not receive excess pressure. The compression tube is cleaned with resilient wire. Visible damage to the hose is a reason for replacement: excess air leaves the tube, and not the pressure switch membrane acts.
- If the cause is not in the tube, continue to remove the pressure switch.
- Disconnect the electrical wire connector. Unreliable (floating) contact at the connector location is the reason for the washing machine to malfunction.
Often manufacturers provide additional latches in the form of latches so that the wires do not disconnect from vibration during washing. Do not try to disconnect the connector using brute force - this will require replacement of the part.
- Remove the sensor by unscrewing the mount at the wall of the machine.
An independent check will help to identify only obvious breakdowns of the part. Only an experienced master can configure a sensor without special measuring equipment.
Independently check the following aspects.
- The safety of body parts. There should be no obvious mechanical damage on the sensor. Violation of the integrity of the device body is unacceptable, this violates the correct operation.
- Clean contacts. They clean the contaminated ones; if they burn strongly, they change the sensor (malfunctions inside the relay are the cause of burning).
- Membrane Integrity To check, a piece of hose of a suitable diameter is connected to the inlet fitting. Having blown into the handset, they listen to whether clicks occur due to shorting or opening of contacts inside the sensor.
The clicks themselves speak only of the integrity of the membrane. The operation of the contacts is checked with a multimeter - when they are closed, the measuring device will show the resistance value "0". Any other readings indicate a relay malfunction.
Reasonability of replacement
It is possible to determine the feasibility of a replacement by comparing the average prices of pressure switches and the cost of washing machines.
|Manufacturer||Pressostat price, rub.|
|Ariston, Indesit (Arcadia)||350 - 750|
|Samsung - DC97-00731A||1500-2400|
If all the signs indicate a malfunction of the device, try to replace it with your own hands.
Any interference with the operation of the washing machine, which is under warranty, entails the refusal of a free warranty repair in service centers.
The self-replacement of the relay is within the capabilities of a person who has experience working with screwdrivers and pliers.
The sensor housing is non-separable. An autopsy will interfere with the performance of the device.
- Get a new sensor. Its type must exactly match the model of the washing machine.
- If the wires are solid, mark the installation location with a marker so as not to confuse when connecting a new pressure switch.
- Dismantle the old relay.
- A compression tube is attached to the new sensor, and it is fixed with a clamp. When attaching, be careful - the plastic fitting is easily damaged by excessive force.
At replacement of the relay establish a new collar. Old fasteners may be damaged during removal and may not provide a reliable connection.
- They fix the pressure switch on the machine body.
- Connect the wiring.
- Check the reliability of the mounts.
- Install the cover of the washing machine.
- Connect to the mains and conduct a test wash.
If all the manipulations were performed in a high-quality manner, the device installed by the manufacturer of the washing machine was installed, and the problem was a sensor malfunction - the repair can be considered completed.
Symptoms of the sensor may also be caused by incorrect operation of other components of the washing machine.
The consequences of improper replacement
Incorrect installation causes malfunctions in the operating modes of the washing machine.
- An excess of water in the tank leads to poor-quality washing, incorrect selection of the operating mode, breakdowns of the electric motor.
- The inclusion of the washing mode in the absence of water in the tank will certainly cause the burner to burn out (a tubular electric heater) - an expensive part.
- Incorrect water level detection by the sensor disrupts the washing program.
Replacing a failed relay with your own hands will save on repair. Objectively evaluate your skills and feel free to proceed with the repair if you think you can handle it.