The first step in central vacuum clog maintenance is prevention.  But there are things you can do to help yourself have fewer clogs.  Avoid sucking up water or damp things – dampness is the biggest culprit of clogs.  Also, avoid long firm objects.  This would be things like pens, toothpicks, safety pins, and paperclips. Just avoiding these two things, will dramatically reduce your chance of getting a clog.

Should you think you have a clog, it is important to identify it as a clog, and not another issue. To identify a clog, unplug the main hose from the central vacuum unit, then flip the manual switch on.  If there is full suction at the unit, you have a clog.  If not, there is a different issue.

Once identified, to remove a clog you need to determine which intakes have a clog.  Do this by sucking a tissue or napkin down each intake. If the napkin or tissue makes it to the central unit, there is no clog. If it does not make it, then there is a clog in that inlet.  Once you have identified the inlets with a clog, simply set a high powered compact vacuum (i.e. a wetvac) up to the intake and suck the clog up.  Once everything is sucked up, turn the central vacuum system on so that it can suck back down.  Then resuck up with the compact vacuum.  Repeat 3 or 4 times. Once the clog is removed, run another napkin or tissue through that intake line, if it makes it through, then the clog is taken care of.  If not, you may need to contact a professional serviceman to help dislodge the clog.