Last updated on February 2nd, 2017
A blocked pressure system on a washing machine can result in various different symptoms. Before deciding to fixing this fault you need to have correctly diagnosed it. It’s not something to speculatively do in the hope that it will fix the fault because the pressure system isn’t always easy to get to and all symptoms have other potential causes.
Here is a list of common symptoms of a blocked pressure system –
- Washing machine won’t go into a spin and after a few minutes of successfully draining the water there is a click and the machine stops. Sometimes if the washing machine is left a while the air slowly escapes and turns off the pressure switch. It will then spin OK – until next time
- Washing machine overfills
- Produces an error code mid-cycle
- Won’t take in water and starts washing with no water inside (may energise the heater!)
Note that all of these symptoms can also be caused by various different faults. To properly diagnose and understand if there is a blockage you need to carefully read and understand how the pressure system in a washing machine works – How a washing machine controls water levels | Faults on pressure system.
The most common symptom is the first one listed above. If this happens there is an easy way to see if it is caused by a blockage. Important: These exact same symptoms can be caused if the water isn’t pumping out properly (or at all) or even a faulty motor. You need to establish if it hasn’t gone into spin because it hasn’t drained the water out, or because it has drained it out but there’s a blocked pressure system preventing the message getting to the program control. Did you hear the water pumping away OK as normal? Unless sure, call an engineer
Testing for a blocked pressure system
There is a quick test that may indicate a blockage. First drain all water from the machine (How to drain the washing machine). With the washing machine totally disconnected from the mains remove the lid and carefully twist and pull the small rubber pressure tubing away from the pressure switch. If you hear a click when the tube comes off this is the trapped air being released. The washing machine should now spin. However, do not let the washing machine take in any water with this tube disconnected because it will over fill and flood!
Now try gently blowing down the tube. Is there any resistance? If you can’t blow down the tube it is blocked but if there is enough water in the drum the water will cause resistance and that’s not the same thing. If it is water you will be able to hear bubbling water when you blow hard.
Remember, if you take off the pressure tubing whilst the washer is full of water you will hear a click, and will feel resistance when blowing down the tube – not because of a blockage in the pressure system – because of the presence of water. If there is resistance, and it isn’t water, blow harder and see if you can clear the blockage. Sometimes a solid blockage can need a lot of pressure to clear through it. If you blow down and clear something so that you have a free passage of air then you have temporarily cleared it. I’ve known this method clear the fault for a several wash cycles, a few months, or even totally, but most of the time it will only clear it for a while and needs fixing properly asap.
Clearing the blockage properly
The only way to properly clear a blockage is to remove the pressure chamber bottle and thoroughly clean it under the tap. If you look at the example picture you can see the gunge is caked inside the bottle and there is no way this blockage can be permanently cleared no matter how many times you blow down the tubing.
As the part is usually located deep inside the machine attached to the main tub you will normally need to partially dismantle the machine to get to it. Don’t forget to check the hole leading into the bottle where it attaches to the drum for blockages too.
Warning: If you leave the small pressure tubing off either the pressure chamber bottle or the pressure switch, or the tubing isn’t air tight when re-fitted then the washing machine will overfill.
Finding the pressure chamber
I’m not able to give specific stripping down instructions. All washing machines are different, and even different washing machines of the same brand can have different methods. The best way though is normally from the front so it’s usually a question of removing the main front panel. This always involves unpeeling the door seal from the rim, which is usually secured with a metal band or spring. Then removing the kick strip at the base of the machine to reveal 3 screws holding the front panel on.
There could be 3 at the top of the panel on older machines which would involve removing the soap drawer and possibly the control panel. Most though are intelligently designed with studs under the control panel that holes in the top of the front panel locate into, so with the screws at the bottom removed the panel should pull down and off. Be aware that the door interlock is attached to the front panel with short wires so be careful not to cause the wires to be pulled. The interlock can easily be broken.
DIY Repair tips
You shouldn’t be messing with washing machines unless you are experienced at repairing and maintaining things and know what you are doing around electrics. Here is some vital advice – 3 good pre repair tips | DIY Washing machine repair warnings: 8 things you should never do
What causes a blocked pressure system?
Blockages are caused by a build up of grease, bacteria and slime and or limescale. Check out how to prevent this in my article here – Causes of grease, slime and black mould inside washing machines If you have a blockage already it is very unlikely you will be able to clear it with maintenance washes or washing machine cleaning products. Believe me I’ve tried.
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