23
375 Caterpillar Standard and Aftercooled/Filtered Operator’s Manual and Parts List
DESCRIPTION
ELECTRICAL SYSTEM, 2.10 
FUNCTIONAL DESCRIPTION
The electrical system consists of the basic electrical 
elements required to operate the compressor and also has 
a system feature that automatically shuts down the 
compressor when a malfunction occurs. The system’s 
components include: an engine starter, battery, alternator/ 
voltage regulator, and a fuel solenoid. It also has a 
compressor discharge temperature switch that will shut the 
compressor down if the compressor temperature exceeds 
250° F (121° C). It has an engine water temperature 
switch set to shut down the compressor when the coolant 
temperature reaches 225° F (107° C) and an oil pressure 
switch that will shut down the compressor if the engine oil 
pressure goes too low. An underspeed sensor shuts down 
the compressor if the engine speed falls below 1500 rpm.
COMPRESSOR SHUTDOWN 2.11 
& WARNING SYSTEM, 
FUNCTIONAL DESCRIPTION
The Shutdown System and Annunciator Module (SSAM) 
continuously monitors the status of the compressor. In the 
event of a shutdown condition, the SSAM will shut down 
the compressor and display (ashing) the appropriate 
code on the instrument panel annunciator light. The 
display will continue ashing until the ignition switch is 
turned OFF. The shutdown codes are:
One ash: high compressor discharge temperature• 
Two ashes: high engine coolant temperature• 
Three ashes: low engine oil pressure• 
Four ashes: low engine speed• 
Five ashes: low fuel level (optional)• 
The SSAM also provides startup logic for the compressor. 
When the ignition switch is in the ON position, the 
annunciator light will illuminate for 30 seconds. During this 
30 second period, pressing the ignition switch will engage 
the engine starter. The low engine speed switch is inactive 
during this startup time interval. By the end of these 30 
seconds, the annunciator light goes out and the engine 
START cycle is disabled. At this time the system runs all 
safety checks including low fuel level (if installed).