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Freightliner Coronado 132 / 122SD. Manual - part 23

12. Lubricate the O-rings with silicone or lithium

grease and install them in the end cover.

13. Install the desiccant cartridge on the end cover.

Turn the cartridge clockwise until the desiccant
cartridge makes contact with the end cover.

14. Place the desiccant cartridge in a vise, and turn

the end cover clockwise an additional 180 to 225
degrees to fully tighten the desiccant cartridge to
the end cover.

NOTE: Desiccant cartridge torque should not
exceed 50 lbf·ft (68 N·m).

15. Place the housing over the desiccant cartridge

and align the mounting holes with the end cover.

IMPORTANT: Replace, do not reuse the Nylok
nuts on the air dryer cover.

16. Install the 6 bolts, 12 washers, and 6 new Nylok

nuts. Torque the Nylok nuts in a star pattern 17
to 24 lbf·ft (23 to 33 N·m). See

Fig. 2

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f421383

7
8

5/16 x 4-1/2 Upper Mounting
Bracket Bolt

Upper Mounting Bracket Strap

Lockwasher

5/16-Inch Nylok Nut

Upper Mounting Bracket

Housing

Nylok Nut

3/8-Inch Special Washer

Desiccant Cartridge

10. O-Ring
11. Safety Valve
12. Lower Mounting Bracket
13. 3/8-Inch Bolt (long)
14. Check Valve Assembly
15. Purge Valve Assembly
16. Purge Valve Capscrew
17. Exhaust Diaphragm

18. Purge Valve
19. 1/4-Inch Tapping Screw
20. Purge Valve Housing
21. Heater and Thermostat

Housing

22. Return Spring
23. Purge Piston
24. 3/8-Inch Bolt
25. End Cover

Fig. 1, AD–9 Air Dryer (exploded view)

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17. Install the air dryer on the lower mounting

bracket. Install the two previously marked bolts,
four washers, and two new Nylok nuts. Torque
the two remaining Nylok nuts 17 to 24 lbf·ft (23
to 33 N·m). Install the bolt, two washers, and a
new Nylok nut in the upper mounting bracket
strap. Torque the upper mounting bracket strap
Nylok nut 80 to 120 lbf·in (900 to 1360 N·cm).

18. Connect and tighten the three air lines. Connect

the harness connector to the heater and thermo-
stat assembly until the lock tab snaps in place.

19. Start the engine, build the air pressure, and

check the air brake system for leaks. If any air
leaks are present, see Group 42 of the vehicle
Workshop Manual for diagnosis and repair
information.

AD–IP

Park the vehicle on a level surface, apply the
parking brakes, and chock the tires.

Using a wrench or a socket, loosen the desiccant
cartridge bolt. Then separate the desiccant car-
tridge from the end cover.

Pull the cartridge bolt out of the cover and re-
move the cartridge.

WARNING

Do not attempt to disassemble the desiccant car-
tridge assembly. Parts for the assembly are not
available and the cartridge contains a 150 lb
spring that cannot be mechanically caged. Disas-
sembly could release the spring, resulting in per-
sonal injury.

Remove and discard both O-rings from the car-
tridge bolt.

Using a clean rag, wipe clean the inside of the
end cover. Clean the cartridge bolt bore in the
end cover, and the sealing surfaces for the large-
and small-diameter desiccant cartridge sealing
rings.

Inspect the end cover for physical damage, then
inspect all air line fittings for corrosion; replace
as necessary.

Clean and inspect the bolt, paying attention to
the threads and O-ring grooves.

IMPORTANT: Use only the grease supplied with
Bendix replacement kits.

Lubricate the O-rings, bolt O-ring grooves, seal-
ing rings, and cartridge grooves. Lubricate the
end cover bore for the bolt.

Install both O-rings on the cartridge bolt, then,
using a twisting motion, insert the assembled
desiccant cartridge bolt in the end cover.

10. Install the desiccant cartridge on the end cover,

making sure the cartridge is properly seated and
flush on the end cover.

NOTE: It may be necessary to rotate the car-
tridge slightly until the anti-rotation lugs are
properly aligned and allow the cartridge to rest
flush against the end cover.

11. Using a wrench or socket, tighten the desiccant

cartridge bolt 70 lbf·ft (95 N·m). Do not over-
torque.

12. Before placing the vehicle in service, perform the

test below.

12.1

Close all reservoir drain cocks.

12.2

Build system pressure to governor cut-
out, and note that the AD-IP air dryer
purges with an audible escape of air.

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09/20/94

Fig. 2, AD–9 End Cover to Housing Torque Pattern

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12.3

Fan the service brakes to reduce system
air pressure to governor cut-in. Note that
the system once again builds to full pres-
sure and is followed by a purge at the
AD-IP air dryer exhaust.

12.4

Check for excessive leakage around the
head of the desiccant cartridge where it
contacts the end cover. With the com-
pressor in loaded mode (compressing
air), apply a soapy solution to these
areas, and observe that any leakage
does not exceed a 1-inch bubble in 1
second. If leakage exceeds this measure,
remove and re-install the desiccant
cartridge.

AD-9si and AD–IS

Park the vehicle on a level surface, apply the
parking brakes, and chock the tires.

Drain the air reservoirs.

Using a strap wrench or equivalent, loosen the
desiccant cartridge. Spin the cartridge off by
hand and discard it. See

Fig. 3

On the new desiccant cartridge, lubricate the
sealing rings with silicone grease.

IMPORTANT: Only use the silicone grease sup-
plied with Bendix replacement kits.

Screw the desiccant cartridge onto the body by
hand until the seal makes contact with the body.
Rotate the cartridge clockwise about one full
turn. Tighten the cartridge firmly.

42–03 Air Dryer Inspection

Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the tires.

Check for moisture in the air brake system by
opening the reservoir drain cocks. Examine the
discharge. Some trace of water in the discharge
is normal. A discharge of a milky gray liquid indi-
cates excessive moisture is present in the air
system and the desiccant cartridge needs to be
replaced. See Group 42 of the vehicle Workshop
Manual for troubleshooting procedures. The fol-
lowing 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-
sidered an indication of poor air dryer per-
formance.

Inspect the air dryer for external damage, and
check that the unit is tightly mounted on the
frame. If the air dryer mounting is loose, See

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f421910

Desiccant Cartridge

Cartridge Sealing Ring

Threaded Base Post

Fig. 3, Desiccant Cartridge Replacement

Brakes

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Group 42 of the vehicle Workshop Manual for
mounting instructions.

Turn on the ignition switch, but do not start the
engine.

Disconnect the harness connector from the air
dryer.

Connect a voltmeter to circuit 94 on the air dry-
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.

Connect a voltmeter between the two terminals
on the air dryer’s harness connector. If voltage is
not found, repair the open in the ground circuit
wiring.

Use an ohmmeter to check resistance between
the terminals on the end cover. See

Fig. 4

. The

end cover contains the heater/thermostat. If the
heater/thermostat is between 40 and 90°F (5 and
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.

Remove the heater/thermostat assembly and
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. If it does operate as outlined, install it.

42–04 Alcohol Evaporator

Cleaning and Inspection

Maintenance is required during both the freeze sea-
son and the off season to keep the alcohol evapora-
tor in good working order.

Off Season

During the off season, drain the unit of alcohol. At
regular engine service intervals, open the drain cock
to remove moisture from the alcohol evaporator. Be-
fore reactivating the evaporator for the next freeze
season, drain, disassemble, inspect, and steam-
clean the unit of any sludge that may have accumu-
lated. It is advisable to replace any rubber parts
when assembling the alcohol evaporator. Perform
this service just before the freeze season.

Freeze Season Reactivation

Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the tires.

Remove the filler cap, and check the cap tet-
raseal.

Remove the capscrews and reservoir from the
cover.

Remove the cover tetraseal.

Drain the air tank, and disconnect the line from
the evaporator outlet. Remove the check-valve
retainer, spring, and disc.

Install the disc, spring, and check-valve retainer,
and connect the line to the evaporator outlet.

Install the cover tetraseal.

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f421384

End Cover Assembly

Heater/Thermostat Terminals

Fig. 4, End Cover Terminals Location

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