SERVICE MANUAL
TROUBLE SHOOTING THE CR BRAKEMASTER UNIT
SYMPTOM
PROBABLE CAUSE
REMEDY
Air is exhausted from exhaust
1. Inlet side of compressor con-
Consider changing compressor
port when compressor is in
nected to outlet side of tur-
inlet connection. Consult ve-
the stand-by mode.
bocharger.
hicle manufacturer.
2. Check valve at outlet port
Clean or replace check valve
stuck open.
assembly.
System air pressure bleeds
1. Leak in air line connection(s).
Tighten or replace fittings.
off rapidly when air using
equipment is not being
2. Leak in air line or reservoir.
Repair or replace faulty item(s).
operated.
3. Check valve at outlet port
Clean or replace check valve
stuck open.
assembly.
Compressor runs continuous-
1. Leak in air line connections.
Tighten ori- replace fittings.
ly (will not go into stand-by
2. Leak in air line or reservoir.
Repair or replace faulty item(s).
mode).
3. Compressor defective.
Rebuild or replace compressor.
4. Unloader valve stuck open.
Clean or replace unloader valve
assembly.
5. Compressor capacity too low
Install larger compressor.
for vehicle.
Compressor goes into "stand-
1. Leak in air system.
Correct leak.
by" mode but cycles rapidly.
2. Check valve in CR Brakemast-
Clean or replace check valve
er outlet port stuck open.
assembly.
3. Defective seal in unloader.
Repair unloader valve.
4. Unloader sleeve defective
Replace sleeve.
Air flows from exhaust port
1. Unloader valve stuck open
Rebuild unloader valve.
when compressor is attempting
2. Seat of unloader valve chipped
Replace seat assembly.
to build up pressure in air
or nicked.
system.
3. Piece of dirt or foreign mater-
Replace seat assembly.
ial stuck in unloader valve.
Compressor attempts to build
1. Refer to "Compressor runs
pressure but system pressure
continuously" of Trouble Shoot-
will not build up
ing Guide.
2. Line between compressor and
Replace line or remove blockage.
exchanger blocked.
3. Check valve in outlet port
Clean outlet and replace check
stuck closed.
valve.
4. Pressure sensing device de-
Replace
fective.
5. Blockage in air line between
Remove blockage.
compresor and sensing device
(Note: If safety valve of ex-
changer opens, blockage is
after unit).
CTS-4079 - CHAPTER XIV - Page 21
