BENDIX AD-IS PuraGuard Service Data - Page 11

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BENDIX

SYMPTOM

1. Dryer is constantly "cycling"

or purging.

AD-IS

AIR DRYER AND RESERVOIR SYSTEM

TROUBLESHOOTING CHART

CAUSE

A. Excessive system leakage.

B. Defective delivery check valve.

C. Defective governor.

D. Compressor unloader mechanism

leaking excessively.

REMEDY

A. Test for excessive system leakage. Allowable leakage

observed at dash gauge:

- Single vehicle - 1 psi/minute.

- Tractor trailer - 3 psi/minute.

Using soap solution, test vehicle for leakage at ﬁ ttings,

drain valves and system valves and any accessories (i.e.

air suspension) connected to the Bendix

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. Build system pressure to governor cut-out. Wait 1 minute for

completion of purge cycle. Using soap solution at exhaust of

purge valve, leakage should not exceed a 1" bubble in less

than 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 "fan" 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 1" bubble in 5 seconds).

Re-grease the seal on the air dryer cartridge before

reinstalling. Be sure the drain valve on the purge reservoir

is not leaking before restoring vehicle to service.

C. Check governor at both "cut-in" and "cut-out" position for (i)

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

exhaust.

D. Remove air strainer, or ﬁ tting, from compressor inlet cavity.

With compressor unloaded, check for unloader piston

leakage. Slight leakage is permissible.

AD-IS

air dryer