Window Cleaning Pump Troubleshooting Guide for Water-Fed Systems

Understanding how your window cleaning pump behaves is essential if you want reliable water flow, steady pressure, and long-lasting equipment. Most pump problems come from simple causes such as airlocks, dirt inside the pump head, faulty pressure switches or electrical issues. This guide explains each common symptom in clear, practical terms so you can diagnose the issue and get back to work with minimal downtime.

Q: "My pump is running but no water is moving"

Q: "My pump is running but the water is at a very low pressure"

• In many cases, the pump head contains trapped air. This prevents the diaphragm from pushing water through the system. See 'How do I clear an airlock in the pump?' further down the page.
• More often it is caused by a dirty pump head. This section—usually black plastic with your inlet and outlet ports—is extremely sensitive to grit, resin grains, or debris. Even tiny particles can stop the pump from working properly, leading to either no water flow or weak, pulsing flow.
• The only real fix is to strip the pump head, flush every part thoroughly under running water, and reassemble it carefully. Expect this job to be wet—keep towels nearby!
• After cleaning the pump head, always ask yourself: how did dirt get in? Contaminated tanks, unfiltered inlet hoses, missing strainers, or resin leaks are the most common causes. Fitting a proper strainer before the pump makes a huge difference.
• Never set up a system with resin before the pump. If the pump pulls water through an RO/DI vessel from the tank, it almost always drags resin beads into the pump head. Even a strainer can’t reliably catch them. The result is repeated pump blockages. Pumps MUST ALWAYS be installed before the resin vessel.

Q: "When I turn on my controller my pump does nothing"

• This usually indicates an electrical problem, especially if you’re confident the pump is receiving power. If voltage is correct and cables are sound, the most likely cause is a faulty pressure switch or a switch stuck in the “off” position due to pressure build-up. Replacement pressure switches are available here.
• However, always check the rest of your wiring: battery terminals, inline fuse, fuse holder, connectors and any crimped joints. Corrosion or loose connections are extremely common faults in van systems.

Q: "Can I pump chemicals through my pump?"

• Standard window-cleaning pumps are designed for water only. Chemicals, detergents or aggressive agents can damage the diaphragm, valves, seals and pressure switch. They also void the guarantee. But do do sell also chemical pumps for soft wash systems.

Q: "I need a window cleaning pump but it needs to run on a higher voltage. Can I get one?"

• Our standard pumps are made to run on **12V DC** because this is ideal for van systems. However, pumps designed for higher voltage applications can often be sourced. Please contact us for advice.

Q: "How do I clear an airlock in the pump?"

• The pump must always be full of water to function correctly. If it runs dry, air becomes trapped inside and the diaphragm cannot generate suction. A quick fix is to remove the outlet hose and suck gently to pull water through until the pump “primes” itself.
• If you have a second pump available, use it to push water into the dry one—this is the fastest method.
• If priming doesn’t work, you may have a dirty pump head. See: 'My pump is running but no water is moving'.

Q: "My pump has been damaged by water getting inside. I thought a water pump would be waterproof?"

• The “wet side” of the pump is waterproof, but the electrical end is not. Pumps must be fitted in a dry position inside the van. Heavy condensation or water dripping onto the casing can eventually wash lubrication from bearings or corrode electrical contacts.

Q: "Will my pump get damaged if it freezes?"

• Most diaphragm pumps survive a light freeze, but this is not guaranteed. Ice can crack the pump head or distort valves. Protect your system in winter by draining hoses and insulating the pump area where possible.

Q: "My pump runs for a few seconds then stops, and keeps doing it over and over again"

• This is a classic sign that the controller calibration is not set correctly. Adjusting the calibration usually solves the pulsing. See our guide to pump controllers here: Pump Controllers.

Keeping your pump clean, protected and wired correctly ensures a stable flow of pure water, better brush performance and far fewer breakdowns. A well-maintained pump saves you time and money, and keeps your water-fed pole system running smoothly throughout the year.