600H, 700HH, 750, 750H, 750HH, 825, 900H, 1050 USER MANUAL SECTION 5
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Table 5-2: Troubleshooting Chart
SYMPTOM PROBABLE CAUSE REMEDY
Compressor will not start No fuel Check fuel level and add fuel if necessary.
Plugged fuel filter Replace the fuel filter element.
Battery Check electrolyte level and add distilled water and 
recharge if necessary.
Loose battery cables; tighten cables.
Dirty battery cables; clean thoroughly.
Plugged air filter Replace the air filter element.
Engine problems may have developed Refer to Engine Operator’s Manual
Instrument panel problems may have 
developed
Refer to Controller Manual. Sullair Part No. 
02250201-742.
Compressor shuts down 
with air demand present
No fuel Check fuel gauge and add fuel if necessary.
Compressor discharge temperature 
switch is open
Cooling air flow is insufficient; clean cooler and 
check for proper ventilation.
Low fluid sump level; add fluid.
Dirty compressor fluid filter; change element.
Thermostatic element is not functioning properly; 
change the thermostatic element.
Defective discharge temperature switch; check for 
a short or open circuit to the engine fuel solenoid. 
Should this checkout normal, it could be possible 
that the temperature switch itself is defective.
Instrument panel problems may have 
developed
Refer to Controller Manual. Sullair Part No. 
02250201-742.
Aftertreatment soot load >100%. Force a regeneration cycle to reduce soot loading. 
If problem persists, contact your local CAT dealer.
Compressor will not build 
up full discharge pressure
Air demand is too great Check service lines for leaks of open valves.
Dirty air filter Check the filter gauges on instrument panel and 
change element if required.
Pressure regulator out of adjustment Adjust regulator according to control adjustment 
instructions in the Maintenance section.
Defective pressure regulator Check diaphragm and replace if necessary (kit 
available).
Defective air inlet cylinder Replace cylinder
Aftertreatment soot load >100%. Force a regeneration cycle to reduce soot loading. 
If problem persists, contact your local CAT dealer.