During normal operation, the pump in the pressure washer switches off when the gun is closed. If the unit does not then switch off automatically, something is wrong with the pressure build-up. The pressure increase gives the pressure switch the signal to close and switch off the pump. A leakage or a defective valve are common causes.
Rising pressure interrupts the power supply to the pump
The pressure created in the high-pressure cleaner by the compression of air has a control function at the same time as the desired water jet. Inside, valves detect the pressure and react accordingly. If the pressure rises after the gun has been closed, the pressure switch interrupts the power supply to the pump. If the gun is opened again by pulling the trigger, the pressure drops and the pressure switch switches the power supply to the pump back on.
If insufficient or no pressure builds up in the pressure washer, one of the following causes is present:
The circuit is no longer tight and has a leak or leaks. The leak can be in several places in the system:
- Hose connections or connecting pieces
- Seals at the hose connections (causes not only blow-off and water leakage, but also the drawing in of air, which reduces the pressure)
Also of interest: Why does the pressure washer stutter?
Pressure switch or valves
Valves or the pressure switch do not react properly because they are defective or dirty.
- Pump and suction valves
- Valve piston chambers
- Pressure switch (defect usually additionally recognisable by water leakage)
- Check valve
- Cover of the piston chambers
- Defective switching relay does not transmit the impulse from the pressure switch
Also of interest: Why does my pressure washer keep pulsing?
The functionality of all components can be impaired or prevented by dirt deposits such as limescale and cleaning agent residues. In many cases, thorough cleaning will help to restore the switching mechanism to working order.
Bridged current flow
Wetness in the unit or a detached cable “bridges” the current interruption. If this is the cause, the unit must be properly repaired before any further operation, otherwise current flow to the outside is possible.