IC Bus CE Series 2020, Operation And Maintenance Manual

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Maintenance
Troubleshooting
No Restriction Reading
Possible Causes How To Check
Plugged fitting or vacuum line Apply vacuum to gauge until locked up at RED zone. Reconnect line and hold in reset button.
Indicator will fully return unless line or fitting is plugged. A slow return is normal due to safety
filter in fitting.
Leak in vacuum line Apply vacuum to gauge until locked up at red zone. Reconnect gauge and close end of line airtight.
Hold in reset button. Indicator will drop slightly and then not move unless vacuum line has a leak.
Leak in gauge Repeat above except close gauge connection airtight.
Engine air flow too low to generate a
restriction reading after being reset Rev engine from idle to full RPM multiple times to increase air flow enough to create an initial reading.
Air cleaner element split open Visually inspect element.
High Restriction Reading
Possible Causes Explanation
Plugged elements Ultra fine particles are difficult to remove and cleaning may not sufficiently lower restriction.
Plugged inner element (if equipped) Replace inner element.
Plugged inlet screens or ducts Check system upstream from restriction tap for debris, damage, or improper installation.
Heavy snow or rain Temporary high restriction can occur during a rain or snow storm and it disappears after drying out.
cold air may be so dense that high restriction may not reduce engine power before elements are
damaged from high vacuum. If gauge is locked up at red zone check elements for damage.
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