BENDIX AD-9 AIR DRYER Manual page 6

B. Thermostat and Heater Operation
Turn off the ignition switch and cool the end cover
assembly to below 40 degrees Fahrenheit. Using an
ohmmeter, check the resistance between the
electrical pins in the female connector. The resistance
should be 1.5 to 3.0 ohms for the 12 volt heater
assembly and 6.8 to 9.0 ohms for the 24 volt heater
assembly. Note: Some early models of the AD-9
air dryer will have resistance readings of 1.0 to 2.5
ohms for the 12 volt heater assembly and 4.8 to 7.2
ohms for the 24 volt heater assembly. If the
resistance is higher than the maximum stated,
replace the purge valve housing assembly, which
includes the heater and thermostat assembly.
Warm the end cover assembly to over 90 degrees
Fahrenheit and again check the resistance. The
resistance should exceed 1000 ohms. If the
resistance values obtained are within the stated
limits, the thermostat and heater assembly is
operating properly. If the resistance values obtained
are outside the stated limits, replace the purge valve
housing assembly, which includes the heater and
thermostat assembly.
REBUILDING THE AD-9
GENERAL
If, after completing the routine operation and leakage tests,
it has been determined that one or more components of the
air dryer requires replacement or maintenance, refer to the
following list to find the appropriate kit(s).
When rebuilding or replacing components of the air dryer
use only genuine Bendix parts. For ease in servicing the
AD-9 ™ air dryer desiccant cartridge assembly, it is
recommended that the air dryer be removed from the vehicle.
MAINTENANCE KITS AVAILABLE:
5005037 Hard Seat Purge Valve Housing Maintenance Kit
5005893 Soft Seat Purge Valve Housing Maintenance Kit
These kits contain the parts necessary to rebuild
the air portion of the purge valve housing and do
not include the heater and thermostat.
107796 Remanufactured
Replacement Kit
This kit contains the parts necessary to change
the desiccant cartridge only.
107794 Desiccant Cartridge Replacement Kit
This kit contains the parts necessary to change
the desiccant cartridge only.
107799 End Cover Check Valve Assembly Replacement
3/4 inch thread size.
107800 End Cover Check Valve Assembly Replacement
1/2 inch thread size.
6
™ AIR DRYER
Desiccant Cartridge
800405 Service New Purge Valve Housing Assembly -
Soft Seat (w/heater and thermo.) 12 volt
system.
5004341 Remanufactured Exchange Purge Valve
Housing Assembly - Soft Seat (w/heater and
thermo.) 12 volt system.
5004479 Service New Purge Valve Housing Assembly -
Hard Seat
(w/heater and thermo.) 12 volt system.
™
5004339 Service New Purge Valve Housing Assembly -
DLU (w/heater and thermo.) 12 volt system.
5004338 Service New Purge Valve Housing Assembly - Soft
Seat (w/heater and thermo.) 24 volt system.
5004342 Remanufactured Exchange Purge Valve Housing
Assembly - Soft Seat (w/heater and thermo.) 24
volt system.
5004480 Service New Valve Housing Assembly - Hard Seat
(w/heater and thermo.) 24 volt system.
5004340 Service New Purge Valve Housing Assembly - DLU
(w/heater and thermo.) 24 volt system.
107695 Complete Mounting Bracket Kit
This kit contains the upper and lower brackets as
well as the necessary hardware items to mount
them.
GENERAL SAFETY GUIDELINES
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle's air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure from
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
TO AVOID
®