Sullair SN55 User Manual page 76

6: Maintenance
Symptom
Compressor shuts
down with air demand
present
Compressor will not
build full discharge
pressure
75
SN55, SN55S, SN55V, SN75, SN75S, SN75V User Manual
Probable cause
Loss of control voltage
Low incoming voltage
Excessive operating pressure
Separator requires mainte-
nance indicated by STS Con-
troller™
Machine programmed for
wrong pressure setting
Defective regulator valve
Defective blowdown valve
Cooling water temperature too
high
Cooling water flow insufficient
Cooler plugged
Cooling air flow restricted
Ambient temperature is too
high
Low fluid level
Clogged filter
Thermal valve not functioning
properly
Water flow regulating valve not
functioning properly
Air demand is too great
Dirty air filter
Inlet valve bleed orifice
plugged
Pressure regulator out of
adjustment
Defective pressure regulator
Defective unload solenoid
valve
02250247-571 R04
Subject to EAR, ECCN EAR99 and related export control restrictions.
Remedy
Check power supply for 24V DC output.
Replace power supply if necessary.
Consult power company.
Reset. If trouble persists, check that line pres-
sure does not exceed maximum operating pres-
sure of the compressor (specified on
nameplate).
Replace separator.
Reprogram using STS Controller.
Regulator valve should cause inlet valve to
close when the pressure switch contacts open.
Repair if defective.
Blowdown valve should exhaust separator/
sump tank pressure to 18 psig (1.2 bar) when
maximum operating pressure is reached.
Repair if defective.
Reduce water temperature to 85°F (29.4°C) or
less. Water-cooled only.
Check water lines and valves (water-cooled
only).
Clean tubes. If plugging persists, install water
conditioner (water-cooled only).
Clean cooler and check for proper ventilation.
Provide sufficient ventilation.
Add fluid.
Change the fluid filter element.
Replace element.
Change (water-cooled only).
Check service lines for leaks or open valves.
Check the filter indicator and inspect and/or
change element if required.
Ensure control line bleed orifice located inside
inlet valve is not plugged.
Adjust regulator according to control adjust-
ment instructions in the Maintenance section.
Replace regulator.
Check that the valve closes when energized.
Replace the coil or the complete valve if defec-
tive.