Ford 2005 Econoline Supplement Manual page 10

Instrumentation
Air filter restriction gauge (if equipped)
The restriction gauge, located on
the upper housing of the air cleaner
assembly, measures the vacuum
inside the air cleaner. The more the
air cleaner is restricted (dirty,
clogged), the higher the vacuum
reading
Check the air filter restriction gauge
whenever the hood is raised to
perform general engine maintenance
at least every 7,500 miles (12,000 km). If the vehicle is operated in
extremely dusty conditions, check the gauge at least every 500 miles
(800 km), or two weeks, whichever comes first.
Change the air filter when the gauge reads 25 inches (635 mm). Engine
performance and fuel economy are adversely affected when the
maximum restriction is reached.
Blowing-out the air filter element with compressed air is not
recommended as the compressed air may damage the filter paper.
Note: It is not possible to determine the level of filter clogging by visual
appearance alone. A filter which appears to be dirty may actually have
several thousand miles (kilometers) of life remaining.
Always use the underhood air filter restriction gauge to
determine when the air filter element needs to be changed. The
warning light on the instrument cluster should not be used
exclusively for determining when the air filter element needs
changing.
10
2005 Econoline (eco)
Supplement
USA (fus)