Compressor cylinder head or
B. Inspect the compressor discharge port and
discharge line restrictions.
discharge line for carbon build-up. If carbon
is detected, check for proper cooling to the
compressor. (See Cause and Remedy (D)
under Symptom 30.) Inspect the discharge
line for kinks and restrictions. Replace
discharge line as necessary.
Worn or burned out
C. Check for proper oil pressure in the
compressor. Minimum required oil pres-
sure; 5 psi engine idling, 15 psi maximum
governed engine rpm. Check for excessive
oil temperature-should not exceed 240° F.
D. Replace or repair the compressor after
determining none of the preceding installa-
tion defects exist.
32. Excessive build-up and
Dirty induction air filter.
A. Inspect engine or compressor air filter and
recovery time. Compressor
replace if necessary.
should be capable of building
Restricted induction line.
B. Inspect the compressor air induction line for
air system from 85-100 psi in
for kinks and restrictions and
40 seconds with engine at
replace as necessary.
full governed rpm. Minimum
compressor performance is
certified to meet Federal
Restricted discharge line or
C. Inspect the compressor discharge port and
requirements by the vehicle
compressor discharge cavity.
line for restrictions and carbon build-up.
manufacturer. Do not
If a carbon build-up is found, check for
downsize the original
proper compressor cooling.
Replace faulty sections of the discharge
Slipping drive components.
D. Check the condition of drive belts and replace
or tighten, whichever is appropriate.
Excessive air system leakage.
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
The pressure drop should not exceed:
1. 2 psi in each reservoir for a single
2. 6 psi in each reservoir for a tractor and
3. 8 psi in each reservoir for a tractor and 2
Sticking unloader pistons
F. Check the operation of the unloading
pistons in the inlet cavity of the com-
pressor. Both pistons should have the
plunger flanges resting on the inlet cavity
floor when the compressor is loaded
(pumping air). If the pistons and plunger are
not fully retracted, check for proper opera-
tion of the compressor air governor. If the