My wife was vacuuming over the weekend and when she withdrew the hose from
the wall, the central vac continued to operate. The only way we could get
it to shut off was to physically unplug it at the main unit (where the bag
is). I checked the contacts at the wall plate - they seem ok - and I
emptied/replaced the bag. Any other ideas as to what the issue might be?
Thanks in advance for any thoughts you could share...
Stuck relay is a good possibility that will be on the vac where the low
voltage wires attach. However it is also possible you have a short
somewhere in the low voltage wire system. Disconnect one of the low voltage
wires from the central unit. and plug it back in. If it still runs the
wiring is OK. if it does not run until you reconnect that low voltage wire
then the problem is the wiring. My guess would be at the outlet that was
being used when the problem was discovered.
I see lots of good advice here already. Might I suggest that, from the way
it occurred, the little "lever" or arm, inside the floor/wall fitting may
simply be "stuck" in the pushed in position? That was the problem with
ours, anyway. When you insert the hose, the metal pipe is one side of the
ckt, the little arm the return part.
I just happened to notice one looked "different" than the others when I
was studying them to see exactly what turned the vac on.
There is a logical way to troubleshoot the system; it's pretty easy to do.
If still no joy but you have access to a meter that can measure the voltage
used in the wires, come on back. It could be done without a meter, but the
meter just makes it easier; less running around. The voltage in the wires
that turn it on are harmless, but beware the 110V ac: THAT is very
Also, if you feel ambitious, it's handy to have a central vac on a GFCI
since it runs unattended all the time. Assuming yours isn't hard wired,
there are plug-in GFCI's available. They're about $9 around here.
Disconnect the low-voltage line from the vac unit
Does the unit still continue to run - if so you have an issue with the
vac unit (stuck solenoid)
Check the disconnected low-voltage line for a short - use a
if short discovered then it's a process of elimination on where it is
located - 1st check the dust-pan outlets (if you have any - sometimes
they don't close correctly and leave a short in the low voltage line)
Work around each of the other outlets - disconnecting the low voltage
line from each of them (a pain I know) and again check for shorts,
with the multi-meter
If they are all disconnected (outlets), and the short is still there -
it's on the line somewhere - look for damage if you can (rodent
I had the opposite - I had an installer rough in the vac pipes and
cables, but he put a kink in the low-voltage line that gave an open
circuit - just as it entered the garage (so I discovered).
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