How to Troubleshoot Central Vacuum Systems
- Begin at START, test each issue, and narrow the problem down to a numbered solution. You can also print a PDF Troubleshooting Chart & Solutions.
- Click the circle to take you directly to the solution on this page below the chart.
- Also use the topics to the right, where many questions have already been answered. If can't find the help you need, please email a troubleshooting central vacuum question or call the number at the top or bottom of this page.
Central vacuum troubleshooting can be done by a homeowner or a qualified dealer. Many times, dealers will be able to pick up on things others may miss, simply because they are involved with these vacuums on a regular basis. Since central vacuum troubleshooting is standard across all brands, you can choose the most capable dealer in your area to help guarantee great service.
Central Vacuum Troubleshooting Solutions
#1 - Electrical Failure.
- If the inlets are Supervalves, plug the power brush directly into the valve. If the power brush works, the problem is in the high voltage lines in the hose - likely a blown fuse in the hose, but also look at #14.
- Check brush for bad neck tilt switch or reset button.
- Put power directly to brush motor to see if the motor is bad.
- Check cord connections from hose to brush.
- Check to see that Supervalves/Electravalves have 110 volts.
#2 - Clog somewhere else in the system.
- Check power brush.
- Check wands.
#3 - Clog vacuum tubing.
- Check fitting just inside inlet and just inside or right at the power unit for stuck debris.
- Isolate exactly where clog is - by determining the inlet furthest from the vacuum unit that is not suctioning well. The clog is between that inlet and the unit and is the one you will be working on. You can also find the clog by running a numbered styrofoam ball through each inlet. Find which balls made it to the power unit.
- Reverse vacuum with another portable vacuum or built-in vacuum (first, disconnect built-in vacuum unit from vacuum PVC line(s) coming from the home). Suck from the inlet that is bad if your hose is long enough.
- Run electrician's fish-tape or plumber's snake, through pipe and try to hook object/clog.
- Put hose end in, plug end to build pressure, then suddenly release. Use your hand to cover/plug the hose. Try this multiple times from various inlets. The release will send a shock wave through the pipes, and over time release the clog.
- You can even plug the hose into the unit, disconnect the intake pipe, and bring the hose to the clogged inlet and suction it out.
- Run paper towel through as a "pigs" towards motor unit, then reverse suck with a portable.
- Run paper towel through from motor unit 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 1 through 6. *If these solutions still do not free up the line - approximate where clog is and locate if accessible. (attic, crawls pace, closet...)
- Cut pipe and feel suction and visually inspect.
- Run paper towel through and listen for humming or vibration - possible nail in pipe or picture hung with toggle into pipe.
- Run small string through from motor unit to inlet with portable then tie heavier string – attach large object to heavier string. (always tie a safety line to large object to pull it back if needed).
- Locate exact location by creating noise w/ ping-pong ball. Insert in inlet and turn on unit (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.)
- Again run paper towel through each inlet.
- If only one inlet is clogged and cannot be fixed, relocate new pipe via existing installation method.
- Pipes that run underground can sometimes coagulate with debris from moisture.
- Route out with long blunt object.
- Run 10 pounds of rice through system into unit, repeat.
- Trench old lines and replace.
- If lines run under concrete driveway, relocate power unit in area where accessible to locate.
- Re-route pipes from section that does not work to section that does work. Abandon any unnecessary lines.
- Check for "wrong way" Y's or T's.
- Any recent construction or workers who might have driven nail into pipes (esp. closet organizers, phones, or alarms)?
#4 Bad inlet - replace inlet & plug hose in again.
- Check to see if inlet is of same type w/contact points. If not; it may have a push button which requires a latching relay.
- When replacing inlet look to see if old one 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 is coming from inlet, additional tape is required on the inlet neck.
#5 - Low voltage wire cut.
- Recent construction done?
- Detached garage with unit located in garage? Recent digging?
- Re-splice broken wire (coppers together and tins together).
- Wires disconnect at unit (on M.D. units only) four coming from vacuum 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).
- Re-route 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).
#6 - Clog in the screen or clog in the hose.
- For bagless, bottom-emptying central vacuums, be sure to reach up into the vacuum unit to find a filter or screen that needs to be cleaned, replaced, or scraped off.
- Reverse the hose at inlet on power unit. Suck it out.
- Drop a butter knife or heavy object through hose - sling it or squeeze hose & twist to get through.
- Shove garden hose through vac hose. Don't turn water on!
#7 Unit is good, pipes have leaks.
- Recent work done on house?
- Recent wallpapering or paneling? Inlet removed or re-installed incorrectly?
- Inlet lid broken?
- Hidden or forgotten inlet?
- Inlets installed in floor; pipe fell down or loose?
- Turn unit on and walk around house listening for a leak.
- Inlet roughed in but not found on finish?
- Pipe running underground has a break in it.
- Recent gardening or tree roots strangling it.
#8 - The Power unit has bad suction.
- If multi-motored unit: are both working?
- Check power unit gaskets and cracks in housing.
- Improper voltage into power unit.
- Loose wires.
- Mini-breaker has malfunctioned.
- On cyclonic unit:
- Lint & debris in motor fan blades.
- Lint & debris on screen on intake.
- Too much back pressure from exhaust line.
- On bag type unit: Excessive amount of very fine plaster dust clogging primary or secondary filter.
- Motor loose.
#9 - Short in power unit.
- Directly isolate low voltage leads alone (disconnect all auxiliary switches).
- Short in relay. *Very rare.
#10 - Short in low voltage system.
- Recent attic work or someone in crawl space?
- Rats chewed through wire?
- Disconnect any splices you can find & check continuity of short.
- 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 the vacuum motor is not turning on. Dead motor.
- 99% of the time, the motor is bad and needs to be replaced. See your Brand Motor Chart for replacement motor and instructions.
- If there is a mini-breaker popped out over an inch, push it in and try the motor again. It may work for a few minutes but shut off again. This is proof the motor is bad. Slapping the canister may get it to start again too.
- Motors last from 800-1100 hours, if your motor is not that old, try replacing the carbon "motor brushes".
- More information on testing motor, relay, transformer, motor brushes, circuit board.
#12 - The power unit is not getting electricity.
- Check house circuit breaker.
- Try vacuum in another outlet.
- Is the circuit breaker the right size for the power unit?
- See what is on the circuit: is it overloaded?
- Continually re-check the system after you do get power to see if it was the vac that tripped the circuit.
- If necessary, have an electrician look at it.
- How to test motor, relay, transformer, brushes, circuit board.
#13 - Transformer and motor not getting power.
- Bad cord?
- Bad transformer- check for spark between 2 low-voltage wires out of transformer.
- Bad relay- check points, arc across to see if it solves it.
- How to test motor, relay, transformer, brushes, circuit board.
#14 - Low voltage in hose is not working.
- If switch feels "mushy" then it needs to be replaced.
- Remove hose from wall and take apart the handle end. Look for lint or other debris in contact points.
- Make sure hose is being fully inserted into inlet.
- Hose may need to be replaced.
By MD Manufacturing
*Note: AirVac Vacuum is a registered trademark of Linear, not M.D. Manufacturing, Inc. Products sold by M.D. Manufacturing, Inc. are not from AirVac Vacuum but are designed to complement a AirVac Central Vacuum. Therefore, parts and products carry warranties from MD Manufacturing and not AirVac Vacuum and thus may alter the warranty provided by AirVac Vacuum.