National 3402, Instruction Manual

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Troubleshooting Guide
Problem Cause Soulution
Insuffi cient vacuum pressure Motors are not on and/or working. Turn both motors on, check motor brushes.
Dustpan improperly seated. Remove dustpan, inspect seal and replace
dustpan.
Filter clogged or improperly seated. Follow Filter Inspection Procedure (See Page
11).
Clogged hose. Remove hose and re-inspect vacuum pressure,
if vacuum pressure returns to normal snake
hose.
Unit is improperly sealed. Block the inlet with a fl at and rigid material to
place the unit under vacuum pressure then
inspect for air leaks.
Material in exaust or on top side of
fi lter Poor fi lter seal or torn fi lter. Follow Filter Inspection Procedure (See Page
11).
Unusual or high pitch noises Motor bearings or motor bushings Follow relevant motor bushing inspection
procedure, section IV. Check motor bearings for
noise by hand.
Worn or poorly seated seals, retainers improp-
erly installed Block the inlet with a fl at and rigid material to
place the unit under vacuum pressure then
remove retainers and turn the unit off. Inspect
the seals for damage, then reseat and secure
components again under vacuum pressure.
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