Suction loss triage

Researched from published specifications and owner reported figures · Convention

Quick answer

When a vacuum stops picking up, check in this order: empty the bin or bag, then hold every filter up to a light, then drop a coin through the hose, then look under the floor head, then check the brush roll for wrapped hair. Those five take about twenty minutes and account for the large majority of machines that get replaced while still working.

The order is the one a service technician works in, cheapest and most likely first. It is a checking order, not a diagnosis of your machine.

Suction loss triage Convention
Best guess is fine. Never is 999.
Check this first Full bin or full bag
1. Full bin or full bag2 min
2. Clogged filter10 min
3. Blockage in the hose or wand10 min
4. Blocked inlet under the floor head5 min
5. Hair wrapped around the brush roll15 min
6. Split hose or a bad seal10 min
Steps that apply to a upright6 of 6
Time to work through all of them52 min
  • Empty it. A bagged machine loses suction well before the bag looks full, because the pores clog long before the volume runs out.
  • A filter that has not been changed in 12 months is the first thing to rule out, whatever the symptom.
  • The first step here that needs a part is "full bin or full bag", and the part is a bag.
How it works: ordered by likelihood x cost to check, cheapest first, with anything the machine type does not have removed. A robot vacuum has no drive belt, so the belt step never appears for one.

The parts these checks point to

Match the part number printed on your own machine against the listing before ordering. A brand match is not a model match.

What this tool does and does not do

It works through the checks in the order a service technician uses, and it tells you what each outcome would mean. It cannot see your machine, so nothing here is a diagnosis of one particular vacuum. Treat every result as a list of things to rule out, and let the part number printed on your own machine have the final word.

No vacuum on this site has been tested by us. Every figure comes from a published manufacturer specification, a defined unit, or a widely used service rule of thumb, and each page says which of those it is using.

Safety

Before you put a hand near a brush roll

Unplug a corded machine, or take the battery out of a cordless one. A thermal cutout resets on its own once the motor cools, and the brush motor can restart without warning.

What never goes in a dry household vacuum

Water, fireplace ash and drywall dust each reach the motor by a different route and each of them ends the machine. If any of those is what caused the problem, the filter set is part of the fix, not an optional extra.

Common questions

Why check the filter before the brush roll?

Because a blocked filter is more common, faster to check and cheaper to fix, and because it produces the same symptom. A machine with a loaded filter has no airflow anywhere in the system, so every other test you run downstream of it gives a misleading result. Rule out the cheap and likely causes before you take anything apart.

How do I know a filter is blocked if it looks clean?

Hold it up to a bright light and look through it. A serviceable filter passes visible light across its whole area. One that is loaded with fine dust looks grey and passes almost none, even when the surface has been tapped out and appears clean. Fine dust sits inside the pleats, not on the face, which is why appearance is a poor guide.

What if I work through everything and it still will not pick up?

At that point the remaining causes are a failed motor, a cracked body letting air in, or a seal that has hardened. Those are the ones worth pricing against a replacement rather than fixing on a hunch. Run the repair or replace tool with a quote in hand, because the answer usually turns on how old the machine already is.

Is it safe to reach into the brush housing?

Only with the machine unplugged, or with the battery physically removed on a cordless model. Brush motors have a thermal cutout that resets on its own once the motor cools, and a machine that is switched on can restart without warning while your hand is in the housing. Unplug first, every time, without exception.

My machine is bagged. Does the bag really matter that much?

More than most owners expect. A paper or fleece bag filters through its pores, and those pores clog with fine dust well before the bag is physically full. A bag at two thirds capacity can already be restricting airflow enough to feel like lost suction. Change on airflow, not on how full it looks.

Does this tool tell me what is wrong with my vacuum?

No, and it deliberately does not try. It gives you the order a service technician checks things in, with the check you run at each step. What it cannot do is see your machine, so every result is a list of things to rule out rather than a verdict. Your own manual and the part numbers on the machine are the final word.

Related on this site

About this page

Every figure here comes from published manufacturer specifications, owner reported measurements and repair documentation, and each is labelled as either a standard or a convention. This is researched general information to help you diagnose and plan, not professional advice, and it cannot tell you what is wrong with one particular machine. Your own manual and the part number printed on your machine are the final word.