Chevrolet TrailBlazer 2003 Manual page 305

When to Inspect
If your vehicle is equipped with a filter change indicator
it will let you know when the filter needs to be
replaced. Inspect the air cleaner/filter every
15,000 miles (25 000 km) and replace the filter if
necessary. Vehicles without a change indicator inspect
the air cleaner/filter every 15,000 miles (25 000 km)
and replace the filter every 30,000 miles (50 000 km).
If you are driving in dusty/dirty conditions, inspect
the filter or change indicator at each engine oil change.
How to Inspect
Locate the filter change indicator. When the change
indicator turns black, or is in the red/orange "change"
zone, replace the filter and reset the indicator. To
inspect the air cleaner/filter, remove the filter from the
vehicle and lightly shake filter to release loose dust and
dirt. If the filter remains "caked" with dirt, a new filter
is required.
To inspect or replace the filter and reset the indicator (if
equipped), do the following:
1. Remove the screws on the engine cleaner/filter and
lift off the cover.
2. Remove the air cleaner/filter from the housing. Care
should be taken to dislodge as little dirt as possible.
3. Install the new engine air cleaner/filter.
4. Reinstall the cover and tighten the screws.
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CAUTION:
Operating the engine with the air cleaner/filter
off can cause you or others to be burned. The
air cleaner not only cleans the air, it helps to
stop flame if the engine backfires. If it isn't there
and the engine backfires, you could be burned.
Don't drive with it off, and be careful working on
the engine with the air cleaner/filter off.
Notice: If the air cleaner/filter is off, a backfire can
cause a damaging engine fire. And, dirt can
easily get into your engine, which will damage it.
Always have the air cleaner/filter in place when
you're driving.
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