How to Fix Central Vacuum Problems

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We love our Central Vacuums. One of the best home cleaning solutions ever created. Not only are these machines easy to use, but they’re more effective about keeping your home allergen and indoor pollutant free. But when your machine is having issues, sometimes it’s hard to diagnose exactly what’s wrong.

See some of these common problems and solutions below. As always, if you have any questions, we’re happy to help. Contact us here and we’ll get back to you a.s.a.p.

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Central Vacuum Clogs
Possible Bad Inlet Valve
Split Central Vac Wiring
Clogged Vacuum Hose
Leaking Central Vac Piping
Bad Suction at Power Unit
Power Unit Electrical Issues
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Central Vacuum Clogs

#1 – Clog between inlet 1 and rest of system
A. Isolate exactly where clog is – by running 1” Styrofoam balls (each numbered) thru each inlet. Find which balls made it to the power unit.
B. Try steps of solution #3 especially B, C, D, F
C. Problem is usually at a “T” shaped pipe fitting.
D. If only one inlet is clogged and cannot be fixed, locate new pipe via existing installation method

#2 – Clog somewhere else in the system
A. Check power brush.
B. Check wands.

#3 – Clog in line between unit and first inlet.
A. Check fitting just inside inlet and just inside the power unit for debris.
B. Reverse vacuum with other portable vacuum or built-in vacuum (first disconnect built-in vacuum from vacuum lines). Suck from inlet that is bad.
C. Run electrician’s fish tape through and try to hook object.
D. Put hose end in, plug end to build pressure, and then suddenly release. Try this multiple times from various inlets.
E. Run paper towel through as “pigs” towards B.I.V. motor toward portable at non-functioning inlet. * Very important: Now run paper towel through all inlets and make sure they all arrive in power unit. If they don’t repeat steps A through F.
F. *If these solutions will still not free up the line: approximate where clog is and locate if accessible. (Attic, crawlspace, closet…)
G. Cut the pipe and feel suction & visual inspection.
H. Run paper towel through and listen for humming or vibration, possible nail in pipe or picture hung with toggle into pipe.
I. Run some string through from B.I.V. to inlet w/ portable then tie heavier string – to heavier string to large object. (always tie a safety line to large object to pull it back if needed).
J. Locate exact location by noise w/ping pong ball in inlet & turn on B.I.V. (remove inlet to get ball in). Find least obvious way of lifting flooring or cutting into back of cupboard or ceiling to access clogged spot. Cut pipe, remove clog, patch back access.
K. Again run paper towel through each inlet.
L. Pipes that run underground can sometimes coagulate with debris from moisture.
i. Route out with blunt object.
ii. Run 10 pounds of rice through system into B.I.V., repeat.
iii. Trench old lines and replace.
iv. If lines run under concrete driveway, relocate power unit area where accessible to locate.
M. Re-route pipes from section which does work to section that does not work. Abandon any unsuccessful lines.
N. Check for “wrong way” Y’s or T’s.
O. Any recent construction or workers who might have driven nails into pipes. (esp. closet organizers, phones, or alarms.)

Possible Bad Inlet Valves

#4 – Bad inlet – replace inlet & plug hose in again.
A. Check to see is of same type w/contact points. If not; it may have a push button, which requires a latching relay.
B. When replacing inlet, look to see if old had tape on inlet neck. If so: put tape in approximate same location on new inlet. When re-installing vacuum, test for air leak: if slight hissing coming from inlet; additional tape required on inlet neck.

Split Central Vac Wiring

#5 – Low voltage wire cut.
A. Recent construction done?
B. Rats?
C. Detached garage with unit located in garage?… Recent digging?
D. Re-splice broken wire (coppers together and tins together).
E. Wires disconnected at unit. (on M.D. units only) 4 coming from vac unit plus at least 2 coming from house. Should be (1 black, 1 red, 1 from house) and (1 black, 1 yellow or red, 1 from house).
F. Re-route any wire from any working inlet or power unit to any section of wire to inlet that does not work. (Run under carpet, behind baseboards, stapled in corners or closets or down inside of walls. Try to tie it to existing bad wire and pull it through).

Clogged Vacuum Hose

#6 – Clog in hose
A. Reverse the hose at inlet on power unit. Suck it out.
B. Drop kitchen knife or heavy object thru hose – sling it or squeeze hose & twist to get through.
C. Shove garden hose through vac hose. (Do not turn water on!)

Leaky Central Vac Piping

#7 – Unit is good, pipes have leaks.
A. Recent work done on house?
B. Recent wallpapering or paneling? Inlet removed or re-installed wrong?
C. Inlet lid broken?
D. Hidden or forgotten inlet?
E. Inlets installed in floor; pipe fell down or loose.
F. Turn unit on and walk around house listening for leaks.
G. Inlet roughed in but not found on finish?
H. Pipe running underground has break in it. Recent gardening or tree has strangled it.

Bad Suction at Power Unit

#8 – The power unit has bad suction.
A. If multi-motored unit: are both working?
B. Check power gaskets and cracks in housing.
C. Improper voltage into power unit.
D. Loose wires.
E. Mini-breaker has malfunctioned.
F. On Cyclonic unit: 1) Unit & debris in motor fan blades; 2) Lint & debris on screen on intake; 3) Too much back pressure from exhaust run too far. Something blocking exhaust line.
G. On bag type unit: Excessive amount of very fine plaster dust clogging primary or secondary filter.
H. Motor loose.

Central Vac Power Unit Electrical Issues

#9 – Short in power unit.
A. Directly isolate low voltage leads alone (disconnect all auxiliary switches).
B. Short in relay. (Very rare)

#10 – Short in low voltage system.
A. Recent attic work or someone in crawlspace?
B. Rats chewed through wire?
C. Disconnect any splices you can find & check continuity of short.
D. Worst case: re-route wire from any other working inlet or wire. (Possibly running wire behind baseboards, under carpet, in closets, or in air ducts).

#11 – Relay getting power but not starting unit.
A. Most likely motor brushes.
B. Isolate motor & see if it works.
C. Check wiring for relay to motor: Does it go thru mini-breaker?
D. After replacing brushes: if it won’t take them; replace motor

#12 – The power unit is not getting electricity.
A. Check house circuit breaker.
B. Try vacuum in another outlet.
C. Is the circuit breaker the right size for the power unit?
D. See what all is on the circuit: is it overloaded?
E. Continually recheck the system after you do get power to see it was the vac that tripped the circuit.
F. If necessary, have an electrician look at it.

#13 – Transformer and motor not getting power.
A. Bad cord?
B. Bad transformer, check for spark between 2 low voltage wires out of transformer.
C. Bad relay, check points, arc across to see id it solves it.

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  1. Pingback: Why a Central Vac is the best vacuum. » VacPartsWarehouse Blog

  2. Hi,
    I have purchased a second-hand, older central vacuum and it does not work (Filtex and it does not have a circuit board). The relay vibrates when I flip the switch, but the unit does not turn on. I isolated the motors by powering with gator clips (15 minutes trial) and they worked. I also tested the transformer according to your FAQ above and that also passed…Could it be anything other than the relay?

    • Above I forgot to mention that the motors did generate what I would assume as sufficient suction for 15 minutes…Not a glitch when I hot-wired them.
      Thanks Again!

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