BENDIX SD-08-2418 Manuel D’Utilisation

4.  Constant exhaust of air at the 

air dryer purge valve exhaust 

or unable to build system 

pressure. (Charge mode.)

A.  Air dryer purge valve leaking 

excessively.

A.  With the compressor loaded, apply a soap solution on the 

purge valve exhaust, to test for excessive leakage. Repair 

or replace the purge valve as necessary.

  Refer to Technical Bulletin TCH-008-040.

B.  Purge valve frozen open - faulty heater 

and thermostat, wiring, blown fuse.  

B.  Refer to paragraph 5 of the Operation and Leakage Tests for 

the heater and thermostat test.

C.  Defective AD-IS air dryer delivery 

check valve. 

C.  Refer to Symptom 1, Remedy B.

D.  Leaking Turbo Cut-Off valve.

D.  Repair or replace the purge valve assembly.

E.  Defective governor. 

E.  Check the governor at both “cut-in” and “cut-out” positions 

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

and exhaust. 

F.  Leaking purge valve control piston 

seals. 

F.  Repair or replace the purge valve assembly.

5.  Cannot build system air 

pressure.

A.  Supply pressure to the air dryer is not 

sufficient.

A.  Ensure the supply pressure to the air dryer is greater than  

110 psi after the system charges.

B.  Kinked or blocked (plugged) discharge 

line.

B.  Check to determine if air passes through discharge line. 

Check for kinks, bends, excessive carbon deposits, or ice 

blockage.

C.  Excessive bends in discharge line 

(water collects and freezes).

C.  Discharge line should be constantly sloping from compressor 

to air dryer with as few bends as possible.

D.  Pressure protection valve(s) in air 

dryer will not open.

D.  Replace air dryer (pressure protection valves are not 

serviceable).

E.  Refer to Symptom 4.

E.  Refer to Symptom 4, Remedy A.

F.  Refer to Symptom 7.

F.   Refer to Symptom 7, Remedies A and B.

6.  Air dryer does not purge or 

exhaust air.

A.  Faulty air dryer purge valve.

A.  After determining air reaches purge valve control port by 

installing a T-fitting with a pressure gauge into the governor 

unloader port, repair purge valve if necessary.

B.  See Causes B, E, and F for Symptom 

#4.  

B.  Refer to Symptom 4, Remedies B, E, and F.

  Also refer to Symptom 1, Remedy B.

7.  Desiccant material being 

expelled from the 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 vibration.

 B.  Check the AD-IS air dryer mounting for looseness or damage.  

Repair the mounting and replace cartridge.

8.  Unsatisfactory desiccant life. A.  Excessive system leakage.

A.  Refer to Symptom 1, Remedy A.

B.  Wrong vehicle application for an 

AD-IS

®

 air dryer.

B.  Refer to Symptom 2, Remedy C.

C.  Compressor passing excessive oil.   C.  Check for proper compressor installation; if the symptoms 

persist, replace the compressor. Refer to Bendix Advanced 

Troubleshooting Guide for Air Brake Compressor (BW1971).