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13

BENDIX

®

AD-IS

®

 AIR DRYER & RESERVOIR SYSTEM 

TROUBLESHOOTING CHART

SYMPTOM

CAUSE

REMEDY

1.  Dryer is constantly cycling 

or purging.

A.  Excessive system leakage.

A.  Test for excessive system leakage.  Allowable leakage 

observed at the dash gauge:

- Single vehicle - 1 psi/minute.
- Tractor/trailer - 3 psi/minute.

Using a soap solution, test the vehicle for leakage at the 
fittings, drain valves and system valves and any accessories 
(i.e. air suspension) connected to the Bendix

®

 AD-IS

®

 air dryer 

auxiliary ports.  If an accessory is suspected to be the cause 
of leakage, disconnect that accessory from the air dryer, plug 
the auxiliary port that it was in, and retest the AD-IS

 

air dryer 

for proper purge cycling.  Repair or replace as necessary.

B.  Defective delivery check valve.

B.  Build system pressure to governor cut-out. Wait one (1) 

minute for the completion of the purge cycle. Using a soap 
solution at the exhaust of the purge valve, leakage should 
not exceed a one inch bubble in less than five (5) seconds. 

If a rapid loss of pressure is found, the following procedure 
will determine if the delivery check valve is malfunctioning:  

Build system pressure to governor cut-out and allow a full 
minute for the normal dryer purge cycle to empty the purge 
reservoir. Switch off the engine and apply and release the 
brakes so that the system pressure reaches governor cut-in.  
The purge valve will return to its closed position.  The purge 
reservoir has a drain valve which is opened by moving the 
center lever away from its closed position. Open the drain 
valve and wait 10 seconds to allow any residual purge 
pressure to be released.  Release the lever, closing the drain 
valve.  Carefully remove the air dryer cartridge using a strap 
wrench and then test for air leaking through the center of 
the threaded boss by applying a soap solution to the area.  
Replace the delivery check valve if there is excessive leakage 
(exceeding a one inch bubble in five (5) seconds).

Grease the seal on the air dryer cartridge before reinstalling.  
Be sure the drain valve on the purge reservoir is not leaking 
before restoring the vehicle to service.  

C.  Defective governor.  

C.  Check the governor at both the “cut-in” and “cut-out” position 

for (i) proper pressures and (ii) excessive leakage at fittings 
and exhaust. 

D.  Compressor unloader mechanism 

leaking excessively.  

D.  Remove the air strainer, or fitting, from compressor inlet cavity. 

With the compressor unloaded, check for unloader piston 
leakage. Slight leakage is permissible. 

Summary of Contents for SD-08-2418

Page 1: ...or Exhaust 23 AUX 2 Auxiliary Delivery Port Pressure Protection Valves 4 Purge Valve RES Governor Reservoir 2 Figure 1 Bendix AD IS AD IS PuraGuard Oil Coalescing Air Dryer Reservoir Systems Desiccant...

Page 2: ...the electrical system in a manner that safely removes all electrical power from the vehicle Never exceed manufacturer s recommended pressures Never connect or disconnect a hose or line containing pres...

Page 3: ...essure protection valves is to protect each reservoir from a pressure loss in the other reservoir or a pressure loss in an air accessory Each of the pressure protection valves in theAD ISair dryer res...

Page 4: ...as adsorption Dry air exits the desiccant cartridge through the center of the base assembly then flows to the delivery check valve through an orifice and into the purge reservoir The delivery check va...

Page 5: ...ck Valve open Primary Port PRI Purge Valve Open Turbo Cut Off Valve Closed Engine Turbo Unloader Port Supply Port Primary Reservoir Pressure Protection Valves Exhaust Safety Valve Purge Reservoir Drai...

Page 6: ...ve housing With the turbo cut off valve seated in the closed position air in the compressor discharge line as well as the AD IS air dryer inlet port cannot enter the air dryer By completing these acti...

Page 7: ...oo close to the air compressor For assistance contact the Bendix TechTeam at 1 800 AIR BRAKE 1 800 247 2725 option 2 or bendix com D In areas where more than a 30 degree range of temperature occurs in...

Page 8: ...cold weather operation as follows A Electric Power to the Dryer Refer to Figure 4 With the ignition or engine kill switch in the RUN position check for voltage to the heater and thermostat assembly us...

Page 9: ...vailable for the servicing of the pressure protection valves Do not attempt to adjust or service the pressure protection valves incorrect pressure protection valve settings can result in the automatic...

Page 10: ...s not build use the following procedure to remove clean and reinstall the delivery check valve DELIVERY CHECK VALVE CLEANING PROCEDURE Note This is only required if system pressure does not build afte...

Page 11: ...for corrosion and replace as necessary ASSEMBLY 1 Lubricate the smaller o ring and check valve body with a heavy duty lithium grease 2 Install this o ring on the check valve body by sliding the o ring...

Page 12: ...12 NOTES...

Page 13: ...governor cut out and allow a full minute for the normal dryer purge cycle to empty the purge reservoir Switch off the engine and apply and release the brakes so that the system pressure reaches gover...

Page 14: ...Air dryer not purging F Refer to Symptom 6 G Purge air exhaust time is insufficient due to excessive system leakage G Refer to Symptom 1 3 Safety valve on the air dryer is popping off or exhausting a...

Page 15: ...air dryer purge valve exhaust may look like whitish liquid or paste or small beads A Faulty dryer cartridge A Replace the Bendix AD IS air dryer cartridge or AD IS air dryer B Excessive dryer vibrati...

Page 16: ...007 2018 Bendix Commercial Vehicle Systems LLC a member of the Knorr Bremse Group 04 18 All Rights Reserved Log on and Learn from the Best On line training that s available when you are 24 7 365 Visit...

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