Vacuum cleaners

This page covers fault finding and repair of vacuum cleaners.

Summary

Vacuum cleaners often experience fairly heavy use, and so are one of the commoner domestic appliances to fail. They are fairly low-tech devices and so not difficult to diagnose or repair.

Safety

On opening a vacuum cleaner, live mains may be exposed. Double check that you've unplugged it before you start. It's a good idea to keep the mains plug on the bench in front of you while you work so as to be sure it's unplugged.

Vacuum cleaners contain powerful electric motors. Keep fingers, loose clothing and children etc. well away from moving parts.

Diagnosis

Bags, filters and blockages

First of all, check that the problem isn't simply that the bag (or the dust canister for bagless models) isn't full.

Check the filter or filters and make sure they're not blocked or in need of replacement. People don't always realize that bagless models also have a filter on the air intake. On some, this is washable.

Make sure the bag and filter(s) are correctly fitted.

Check for a blocked hose. You should hear the motor slow down markedly when you disconnect it if the hose has a blockage.

Plug, fuse and lead

Check that the plug isn't cracked, the cable grip is gripping the cable, and that lead is in good condition, with no cracked insulation. If any damage to the lead is confined to one end you should be able to cut off the damaged section and reconnect it as a slightly shortened lead.

Open the plug, check the fuse and check the screw terminals are tight.

Brush

For an upright machine or one with a rotating brush attachment, check the brush. This commonly gets jammed with hairs which get twisted around it. Check the belt which drives it. This may be worn or broken.

As the "business end" of the machine, the surrounding plastic parts take the most punishment. Sometimes a plastic part gets broken, preventing the brush from rotating freely or tensioning the belt.

Motor and other internal parts

Any further diagnosis and repair is likely to require disassembly. You will have to inspect the machine to determine which screws are likely to give you the access you need. Sometimes one or more may be security screws requiring a security screwdriver bit, or some of them may be deeply recessed in a hole which is too narrow for the universal screwdriver extension needed to reach the screw. Sometimes you can get purchase on the screw with a small flat screwdriver blade but you risk damaging the screw and making it impossible to remove even with the correct screwdriver, or damaging the screwdriver itself.

With the machine open you should be able to use a test meter to check electrical continuity from the plug through to the switch and the motor, though for a multi- or variable-speed machine you will need to trace the wiring and understand how it works.

With the machine open, you should be able to see whether dust has got into places it shouldn't, maybe because of a badly fitting seal or faulty filter. In particular, check the motor. Review the electric motors page if you're not familiar with how they work.

Check that the bearings aren't clogged with dirt and lubricate them. Clean the commutator with switch cleaner or isopropyl alcohol on a tissue. Check that the motor brushes are free to move up and down in their howsing and that the springs are pressing them against the commutator.

If the motor has been laboring due to anything that prevents it turning freely, it may have been overheating. It may also overheat if a blocked air filter impedes the flow of air required to cool it. There may be a thermal cut-out to protect it, which automatically when it cools down, but if not or if the cut-out has been tripping repeatedly, then check for signs of overheating in the motor, in a bad case, charring of the insulation.

For bagless cyclone vacuums, if the dust canister is overfilled, the pre-motor filter will get blocked. Some of these (e.g. Dyson) are washable. People often don't realise these vacuums have filters which need occasional cleaning.

If filters or air path get blocked, motor cooling which relies on the airflow will become ineffective, and the motor may overheat. This may result in the motor cutting out for 10 mins whilst it cools, but it can also permanently damage the motor, which then causes it to overheat even with enough airflow. Overheating will eventually burn out the windings - careful inspection of the windings may reveal overheated areas or even broken wires.

In theory, motor brushes can wear out too, but I don't think I've actually seen this in a vacuum cleaner yet.