BENDIX BW2234 User Manual

2.  Water in vehicle reservoirs

A.  Maximum air dryer inlet temperature is 

exceeded due to improper discharge 
line length. 

A.  Check for excessive carbon build up in compressor discharge 

line.  Replace if required.  Make certain that discharge line 
length is at least 6 ft. Increase discharge line length and/or 
diameter to reduce air dryer inlet temperature.

B.  Air system charged from outside 

air source (outside air not passing 
through air dryer).  

B.  If system must have outside air fi ll provision, outside air should 

pass through air dryer. 

C.  Excessive air usage - Air dryer not 

compatible with vehicle air system 
requirement (Improper air dryer/
vehicle application)

C.  Refer to Bendix Advanced Troubleshooting Guide for Air 

Brake Compressors (BW1971) for proper application of the 
Bendix

®

 AD-IS

®

 air dryer and reservoir system.  An extended 

purge model (Bendix

®

 AD-IS

® 

EP) is available for many higher 

air usage vehicles, such as city buses and construction 
vehicles.

 

If the vehicle is equipped with high air usage accessories 
such as trailer pump-off systems or central tire infl ation, the 
air for these accessories must by-pass the dryer reservoir 
system.

D.  Desiccant requires replacement. 

D.  Replace desiccant cartridge assembly.

E.  Air by-passes desiccant cartridge 

assembly.

E.  If vehicle uses Holset compressor, inspect feedback check 

valve for proper installation and operation. 

F.  Air dryer not purging. 

F.  Refer to Symptom 6.

G.  Purge (air exhaust) time insuffi cient 

due to excessive system leakage. 

G.  Refer to Symptom 1.

3.  Safety valve on air dryer 

“popping off” or exhausting 
air.  

A.  Defective AD-IS air dryer and reservoir 

system delivery check valve.  

A.  Test to determine if air is passing through check valve. Repair 

or replace.  Refer to Symptom 1, Remedy B.

B.  Safety valve setting too low (<150 p.s.i.) B.  Replace safety valve.
C.  System pressure too high (>135 p.s.i.) C.  Test with accurate gauge. Replace governor if necessary.

D.  Excessive pressure pulsations from 

compressor. (Typical single cylinder 
type).  

D.  Increase volume in discharge line. This can be accomplished 

by adding a 90 cubic inch (or larger) reservoir between the 
compressor and the AD-IS

®

 air dryer and reservoir system.

4.  Constant exhaust of air at air 

dryer purge valve exhaust 
or unable to build system 
pressure. (Charge mode.)

A.  Air dryer purge valve leaking 

excessively.

A.  With compressor loaded, apply soap solution on purge valve 

exhaust, to test for excessive leakage. Repair or replace 
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 

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 purge valve assembly.

E.  Defective governor. 

E.  Check governor at both “cut-in” and “cut-out” position for (i) 

proper pressures and (ii) excessive leakage at fi ttings and 
exhaust. 

F.  Leaking purge valve control piston 

seals. 

F.  Repair or replace purge valve assembly.