BENDIX BA-921 COMPRESSOR-STD-CLOSED ROOM Service Data Sheet page 28

Symptom:
9.0 Air brake
charging system
seems slow to
build pressure.
(continued)
Dash gauges.
Engine Oil Quality
Inadequate oil change intervals, the formulation of the
oil and/or the quality of oil fi lter used can all lead to poor
oil quality. These can increase the rate at which carbon
builds up in the discharge line. Bendix recommends oil
soot (solids) be maintained at less than 3%.
(g)
Partly collapsed
inlet line shown.
A-10
What it may indicate:
(f) Restricted discharge line.
(f)
Kinked discharge line shown.
(g) Restricted air inlet (not enough air
to compressor).
(h) Poorly filtered inlet air (poor air
quality to compressor).
(i) Compressor malfunction.
What you should do:
If discharge line is restricted:
By more than 1/16" carbon build-up,
replace the discharge line (see Table A,
column 2, on page A-3 for recommended
size) and go to Test 3 on page A-14.
By other restrictions (e.g. kinks).
Replace the discharge line. See Table A,
column 2, on page A-3 for recommended
size. Re test for air build. Return vehicle
to service or, if problem persists, go to
9.0(a).
The discharge line must maintain a
constant slope down from the compressor
to the air dryer inlet fi tting to avoid low points
where ice may form and block the fl ow. If,
instead, ice blockages occur at the air dryer
inlet, insulation may be added here, or if the
inlet fi tting is a typical 90 degree fi tting, it
may be changed to a straight or 45 degree
fi tting. For more information on how to
help prevent discharge line freeze-ups, see
Bendix Bulletins TCH-08-21 and TCH-08-22
(Appendix B). Shorter discharge line
lengths or insulation may be required in cold
climates.
Check compressor air inlet line for restric-
tions, brittleness, soft or sagging hose con-
ditions etc. Repair as necessary. Refer to
vehicle manufacturer's guidelines for inlet
line size.
Check the engine air fi lter and service if
necessary (if possible, check the air fi lter
usage indicator).
Check for leaking, damaged or defective
compressor air inlet components (e.g.
induction line, fi ttings, gaskets, fi lter bodies,
etc.). Repair inlet components as needed.
Note: Dirt ingestion will damage compressor
and is not covered under warranty.
Replace the compressor only after making
certain that none of the preceding conditions,
9.0 (a) through 9.0 (h), exist.