Specifications

14
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COMPRESSOR TROUBLESHOOTING CHART (Continued)
SYMPTOMS
B. Inspect drive gear and couplings and engine for
excessive wear. Replace as necessary.
(Nonmetallic gears should be replaced when the
compressor is changed.) Drive gear should be
metal-type on Detroit Diesel engine.
C. Inspect the compressor discharge port and
discharge line for carbon build-up. If carbon is
detected, check for proper cooling to the
compressor. (See Cause and Remedy (D) under
Symptom #1.) Inspect the discharge line for
kinks and restrictions. Replace discharge line as
necessary.
D. Check for proper oil pressure in the compressor.
Minimum required oil pressure: 5 psi engine
idling, 15 psi maximum governed engine rpm.
Check for excessive oil temperature—should not
exceed 240 degrees Fahrenheit.
E. Replace or repair the compressor after
determining none of the preceding installation
defects exist.
A. Inspect engine or compressor air filter and
replace if necessary.
B. Inspect the compressor air induction line for
kinks and restrictions and replace as necessary.
C. Inspect the compressor discharge port and line
for restrictions and carbon build-up. If a carbon
build-up is found, check for proper compressor
cooling. Replace faulty sections of the discharge
line.
D. Check for faulty drive gears and couplings and
replace as necessary. Check the condition of
drive belts and replace or tighten, whichever is
appropriate.
E. Test for excessive system leakage and repair as
necessary. Use the following as a guide: Build
system pressure to governor cutout and allow
the pressure to stabilize for one minute. Using
the dash gauge, note the system pressure and
the pressure drop after two minutes.
The pressure drop for Pre-1975 vehicles should
not exceed:
1. 4 psi for a single vehicle.
2. 6 psi for a tractor trailer.
3. 10 psi for a tractor and 2 trailers.
B. Excessively worn drive
couplings or gears.
CAUSE
REMEDY
A. Dirty induction air filter.
B. Restricted induction
line.
3. Excessive build-up and
recover time.
Compressor should be
capable of building air
system from 85-100 psi
in 40 seconds with
engine at full governed
rpm. Minimum
compressor
performance is certified
to meet Federal
requirements by the
vehicle manufacturer.
Do not downsize the
original equipment
compressor.
C. Restricted discharge
line or compressor
discharge cavity.
D. Slipping drive
components.
E. Excessive air system
leakage.
C. Compressor cylinder
head or discharge line
restrictions.
D. Worn or burned out
bearings.
E. Faulty compressor.