Clogs are a common problem with central vacuum systems. The good news is that you can remove most clogs without calling a repairman. The trick is finding where the clog is in your system. Once you locate the clog, there are a few things that you can do to get your system up and running again. You just need to become familiar with your system and know what to look for.
Empty the dirt canister or receptacle that is located on the bottom of the unit. Unhook the latches and pull the bottom off. Empty the trash into a trash can. Look inside the receptacle at the filter. It if is brown or full of debris, replace it. Put the canister back on the unit and hook the latches.
Hold a facial tissue in front of each wall valve. Open the valve and allow the tissue to be sucked into the unit. Check the trash receptacle to see if the tissue made it down. Move to the next valve if there was no clog.
Turn the switch off on the side of the unit manually. Use a wet-dry vacuum to apply suction to the wall valve where you find a clog. The reverse suction should clear the clog.
Run a plumber's snake through the wall valve if the reverse suction of the wet-dry vacuum did not work. The snake should push the clog out.