OPERATOR'S MANUAL

Air System Preventive Maintenance
– 200 – Y53-6027
Medium Duty (R05/09)
pressors. After completing any repairs to the air system,
always test for air leaks, and check the brakes for safe opera-
tion before putting the vehicle in service.
According to
Table 5, “Air System Scheduled Mainte-
nance,” Page 196
:
• Inspect compressor air filter element, if so equipped, and
replace element if clogged. Check compressor mounting
and drive for alignment and belt tension. Adjust if necessary.
• Remove compressor discharge valve cap nuts and
check for presence of excessive carbon. If excessive car-
bon is found, clean or replace the compressor cylinder
head. Also, check compressor discharge line for carbon,
and clean or replace the discharge line if necessary.
• Disassemble compressor and thoroughly clean and
inspect all parts. Repair or replace all worn or damaged
parts, or replace compressor with a factory exchange
unit.
CAUTION: When draining the engine cooling
system is required, to prevent damage from
freezing, the compressor must also be drained
at the cylinder head and block. Engine damage
could occur if the cooling system is not periodi-
cally drained and maintained. See
“Engine Cool-
ing System,” Page 178, and the Medium Duty
Maintenance Manual for further information.
Air Dryer
WARNING! Use of incorrect air dryer could
cause air system failure, leading to loss of vehi-
cle control and serious personal injury or death.
If your vehicle is equipped with a Bendix AD-IS
air dryer, it is important that future replacements
be identical or similar in design.
Any deviation from the Bendix AD-IS type air dryer would
require changes to the vehicle air system. Some vehicles
use a dual air system consisting of a wet tank, forward dry
tank, and rear dry tank. The dry tanks have a single-check
valve in the tank inlet. The check valves prevent a com-
plete loss of air in the event of an air system failure (tank
or hose failure). This ensures a controlled stop (with