Chevrolet T-Series Owner's Manual page 211

The purge tank is equipped with a manual drain
valve that must be drained every day. See
"Air Brake Systems" for the manual drain
procedure. The dryer is mounted on the driver
side frame rail.
Electric Air Compressor
Your vehicle may have an electric air compressor.
This compressor is used to run options that
require pressurized air, such as air horn, air seat,
exhaust restrictor, or an exhaust brake.
The dryer has a filter that
you need to change at
intervals. See Scheduled
Maintenance on
page 269 for more about
servicing this filter.
The air compressor is used when vehicles are not
equipped with an air brake system.
It is recommended that this system be drained on
a weekly basis.
Clutch Pedal Free Travel
Normal clutch pedal free play is 1.5 to 2 inches
(38 to 51 mm) measured from the floorboard. If the
free play is less than 1.25 inches (32 mm),
adjustment is required.
The air supply for this
system must be
maintained by releasing
the drain valve to
eject any moisture that
may have built up in
the system.
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