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How to Diagnose Pressure Washer Electrical Problems

Pressure washers can be found in many households nowadays, but they can suffer from common problems. If your pressure washer is dead, trips the fuse board or electrics in your home or stalls - this video will help you diagnose the problem and could hopefully be the first step to you going on to repair it yourself.

If you are unsure where to start there’s no need to panic. We’ll talk you through how to diagnose some different electrical problems relating to your pressure washer, by using a multimeter.

A multimeter is a versatile tool that can be used to measure electrical resistance within a circuit, just as you would use a ruler to measure distance.

If you've got a faulty appliance within your home and you're not sure what's causing the fault, a great way to find out is to use a multimeter.

This video shows an example on how to remove or replace the part on a typical machine, some models may be different but the procedure should be similar.

What You Will Need:

Switch Off Your Appliance

Safety First! Please make sure that you have switched your appliance off at the mains before starting your repair.

We’ll now go through some examples of the parts that could be causing your pressure washer to not work.

The Fuse

If the pressure washer does not start, then the first thing to check is the fuse in the plug. The reading you're looking for is the same as it would be when connecting the two probes of the multimeter together (as you can see in the example of this video, this fuse is actually fine).

Please Note: The following part checks require you to access the inside of the pressure washer. To do this you need to remove the two halves of the pressure washer case by undoing the screws that are keeping it together.

Once you have access to the electrical items inside your pressure washer, you can start to look at the following parts.

Check The Whole Circuit

Step 1 - Test Plug With Multimeter

Put one probe on the neutral of the plug and one on the live, and if the reading has not changed on the multimeter, there's obviously a break somewhere in this circuit.

Step 2 - Check Switch Reading On Neutral

Check from the plug up to the switch through the cable, by keeping one probe on the neutral of the plug to the neutral wire on the switch, and in this instance on the video here we can see the reading is very low resistance so we have continuity.

Step 3 - Check Switch Reading On Live

Check the same with the live - so one probe on the live on the plug to the live on the switch, again in the instance on this video it displays as having very low resistance - so no problems there.

Step 4 - Check Motor

Check from the switch to the motor - so one probe on the live on the switch to the live on the motor, again low readings on this example in this video - so no problems from the switch to the motor. You can then also do the same with the neutral - again in this instance it shows a very low resistance.

Time to s check now across the motor - and here we now have a problem. There is a very high reading which indicates that there is a problem with the motor.

Motor Capacitor

Some motors like the one on this Karcher K5 compact pressure washer will feature a capacitor. If you turn your pressure washer on and the motor stops or makes a loud buzzing noise, or it buzzes continuously, then you can suspect and examine the capacitor.

You may notice bulges on the capacitor or burn marks and blackening on it.

If the pressure washer trips the fuse board or blows the electrics in your home, make sure there's no water in the switch or the other electrical items - and again examine the capacitor if your model carries one.

Measure The Resistance Across The Plug

It's also a good idea to measure the resistance across the plug so put one probe of your multimeter on the live pin and one on the neutral, and you're looking for a reading of between 5 and 12 ohms.


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