Chapter 5 Compressor Lubrication & Maintenance
49
Compressor Troubleshooting
This section includes instructions for troubleshooting the equipment following a malfunction.
Each problem symptom for a component or system is followed by a list of probable causes and
suggested resolutions.
In general, perform the procedures in the order in which they are listed. Vary the order if needed
due to specific conditions.
PROBLEM
CAUSE
RESOLUTION
Truck Engine Will Not Start
Vehicle engine problem.
Check vehicle manual.
High temperature.
The compressor shutdown safety
switch causes the vehicle engine to
shut down on vehicles with manual
transmissions. If this occurs, restart
the truck once the temperature
drops, or by disengaging the PTO.
If the compressor high-temperature
switch has shut off the engine, take
the vehicle for service.
Unplanned Shutdown
Engine problem.
Check fuel level, truck dash gauges
and indicators.
Check compressor discharge
temperature / switch gauge.
If the relay circuit is tripped, the 12V
DC solenoid will lose power and
divert hydraulic oil back to the
reservoir. The blowdown switch
and the temperature switchgauge
will not allow power to the hydraulic
solenoid until the air has blown
down and the temperature has
dropped into its normal operating
range. Take for service if high
temperature shutdown has
occurred.
Low compressor oil.
Check compressor oil level. Add if
needed.
Airflow obstruction.
Check the oil cooler for dirt, slush,
ice on fins, or other obstructions.
Hose or wiring break.
Check for broken hoses, oil lines, or
loose or broken wires.
Low Discharge Pressure
Too much air demand.
If air tools require more air than the
compressor can produce, change
tools.
Open service valve.
Close service valve.
Leaks in service lines.
Repair line leaks
