Chevrolet B7 2001 Owner's Manual page 140

Air Dryer (If Equipped) If your vehicle has air brakes, it may have an air dryer.
This collects and removes dirt, moisture or other foreign
matter from the air prior to entering the brake system.
It is mounted on the left frame rail.
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If your dryer is a Bendix Westinghouse, it has a
filter that you need to change at intervals. See your
Maintenance Schedule for more about servicing
this filter.
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