freightliner Argosy COE Maintenance Manual page 104

Brakes
6
4
1 & 9
7
09/20/94
Fig. 2, End Cover to Housing Torque Pattern
cates excessive moisture is present in the air
system and the desiccant cartridge needs to be
replaced. See Group 42 of the Century Class
Trucks Workshop Manual for troubleshooting pro-
cedures. The following conditions could cause
small amounts of moisture to be found in the air
system:
• An outside air source has been used to
charge the air brake system. This air did
not pass through the drying bed.
• Air usage is unusually high and not normal.
This may be due to accessory air demands
or some unusual air requirement that does
not allow the compressor to load and un-
load in a normal fashion. Check for air sys-
tem leaks.
• The air dryer has been installed on a sys-
tem that had previously been operated
without an air dryer. This type of system
will be saturated with moisture, and several
weeks of operation may be needed to fully
dry the system.
• The temperature range in your area fluctu-
ates more than 30 degrees in one day.
Small amounts of water can accumulate in
the air brake system due to condensation.
Under these conditions, the presence of
moisture is normal and should not be con-
Century Class Trucks Maintenance Manual, April 2005
2
2. Inspect the air dryer for external damage, and
5
3. Turn on the ignition switch, but don't start the
4. Disconnect the harness connector from the air
3
5. Connect a voltmeter to circuit 94 on the air dry-
8
6. Connect a voltmeter between the two terminals
f420544a
7. Use an ohmmeter to check resistance between
8. Remove the heater/thermostat assembly and
sidered an indication of poor air dryer per-
formance.
check that the unit is tightly mounted on the
frame. If the air dryer mounting is loose, See
Group 42 of the Century Class Trucks Workshop
Manual for mounting instructions.
engine.
dryer.
er's harness connector and to a body ground
point. Check for battery voltage. If voltage is not
found, check and repair the open or short to
ground in wire 94.
on the air dryer's harness connector. If voltage is
not found, repair the open in the ground circuit
wiring.
the terminals on the end cover. See
end cover contains the heater/thermostat. If the
heater/thermostat is between 40° and 90°F (5° to
32°C), the heater/thermostat measured resis-
tance will be infinite ohms. If the measured resis-
tance is less than infinity, replace the
heater/thermostat.
place it in a freezer for about five minutes to cool
it below 40°F (5°C). Remove the cold
heater/thermostat assembly and check resis-
tance between the heater/thermostat terminals.
Resistance should be 1.5 to 3.0 ohms. As the
temperature of the heater/thermostat assembly
increases, the ohm reading will increase. When
the temperature goes above 45°F (7°C) mea-
sured resistance should be infinite ohms. If the
heater/thermostat does not operate as outlined,
replace it.
42
Fig. 3. The
42/3