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Step by step guide

Smart: replace switch box

Servicing our pressure washers are quite straight forward and could be done by most people by following the step-by-step instructions in this manual. Please go trough the whole manual before starting work on your pressure washer to make sure you understand the procedure and that you have the necessary tools to complete the task.

Always unplug the pressure washer from both the mains power and the water outlet before starting the service. Even though power and water is disconnected there may be pressurized water in the hose. Discharge this pressure by pulling the trigger on the gun. Make sure your work area is clean and appropriate for the work you are about to do. There will usually be a small amount of water inside the pump and hose. If you are doing a 10-year service, then be prepared to collect the used oil from the oil chamber. Please dispose of the oil in accordance with local law and regulations. ISO 46 hydraulic oil can be substituted with similar non detergent oil of the same viscosity.

00. Parts and tools

An overview of what is needed to do this service.

01. Remove the water filter

Unscrew the water filter and remove it.

02. Remove screws

Release the short pressure hose from the pump outlet. Unscrew the six T25 screws from the back cabinet.

03. Remove the front cover

Remove the front cover. Then remove the on/off knob.

04. Remove screws

Unscrew the three T25 screws securing the motor/pump.

05. Disconnect the soft start box

Disconnect the power cable from the soft start box.

06. Remove the motor/pump

Carefully lift out the motor/pump assembly.

07. Remove inlet pipe

With the motor/pump out, remove the U-pin securing the inlet pipe. A flat head screwdriver or similar tool is useful to pry out this pin.

Then remove the inlet pipe from the pump head.

08. Remove the switch box

Remove the switch box by pulling it in the direction indicated. It is press fitted onto the start/stop valve on the pump.

Also release the soft start box from its fixture.

09. Remove the motor cowling

To get access to the motor power cables we need to remove the motor cowling. Put the switch and soft start box to the side.

Remove one T25 screw from the cowling and bend the two flaps where the hooks of the lower cowling engages. Lift off the top and bottom cowling.

10. Disconnect the motor power cords

Push down the small tab on the female connector while gently pulling the cable. Release both spade connectors from the motor wiring and pull them trough the plastic frame.

11. Open the old switch box

If your switch box came without a soft start box/cable you need to open the old switch box to extract the soft start cabling. If it comes with a soft start box, you can skip ahead to step 15.

Unscrew the 5 Phillips head screws holding the lid.


12. Extract the soft start box

Remove the lid from the switch box.

Release the soft start power cable from the main switch. To release the cable, you need to press down the small locking tab on the spade connector.

13. Attach the soft start box to the new switch box

Open the lid on your new switch box and connect the soft start power cable to the main switch. It does not matter which way you connect it to the main switch as this is alternating current.

Make sure that the sliding and rotating pin is correctly situated before closing the lid.


14. Close the switch box

Fasten the lid using 5 Phillips head screws.

15. Connect the motor power cords

Take the two motor power cables and pull them trough the plastic frame. Connect the female spade connector to the male spade connector. The order of the connection is irrelevant since the motor runs on AC power.

16. Fit the motor cowling

Put the switch and soft start box to the side.

Place the motor/pump assembly into the lower half of the motor cowling. Once happy with the placement, fit the top half of the cowling.

Make sure the to locking hooks on the top cowling engages the slots in the lower cowling. Secure the assembly with 1 T25 screw.

17. Connect the soft start box

Connect the power cable to the soft start box.

Put the on/off switch knob back on to the switch box.

18. Attach the switch box

Fit the soft start box onto its fixture.

Attach the new switch box to the pump. You need to put decent amount of pressure to get the box firmly seated on the start/stop valve. It should pop into place.

19. Attach the inlet pipe

Reattach the inlet pipe.

Secure it using a U-pin, use a small hammer or something similar to tap it into place.

20. Place motor/pump back into the rear cabinet

Turn the motor/pump unit so that the switch box and water inlet is facing up and place it back into the rear cabinet.

21. Connect the power cable

Connect the power cable to the soft start box.

Put the on/off switch knob back on to the switch box.

22. Secure the motor/pump

Secure the motor/pump and the switch box using the three T25 screws.

23. Fit the front cover

Carefully fit the front cover to the back cabinet of the pressure washer.

Make sure the on/off button is properly positioned so that it can operate freely.

24. Secure the front cover

Make sure that the front and back cover is perfectly aligned. Secure the front cover using six T25 screws.

Attach the short pressure hose to the outlet connector at the back

25. Fit the water filter

Check that the filter cassette is clean, then refit the water filter.

26. First start after service

Congratulations with finishing the service of your AVA product.

It is now time to do the first start after service.


  1. Start by connecting the pressure gun to the hose.
  2. Connect water.
  3. Make sure no water is leaking from the inside or anywhere else on the pressure washer.
  4. Pull the trigger and let the water flow until there is no more air coming out.
  5. Connect the power cord.
  6. Turn on the pressure washer.
  7. Pull the trigger and let water run for a minute before connecting a nozzle.
  8. Connect the nozzle. Use the pressure washer and make sure it is operating as normal.

27. Troubleshooting

Water is leaking from the inside

•Disconnect the power and open the pressure washer to locate the leak. Take necessary action to remedy any leaks.

Motor runs and won't stop when you release the trigger

•This is most likely due to an improper seating of the switch box on the start/stop valve. Open the machine and check that the switch box is correctly seated.•

The pressure washer won't turn on

•Check that the power cable is connected.

•Check that the circuit breaker has not been tripped.

•Check that the fuse in the power plug is intact (UK models only).

•Open the machine and check that all the internal cabling is connected.

Poor performance/pressure

•Improper assembly or dirt/debris in the pump. Check that the pump and especially the main valve for foreign objects/debris. Make sure that the spring in the main valve is correctly seated and working as intended.