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rack and rotate the valve. Located on the ends of the
cylinders are adjusting screws which limit the travel of
the actuator. When looking at the rear of the compres-
sor, the adjusting screw on the right on the compressor
adjusts the fully closed (full–load) position of the valve.
The full load position of the actuator may be checked
by removing the adjusting screw at the unloaded end
of the actuator (left side of the compressor) and using
a rod to push the pistons to the full load position. The
rod must be clean and free of burrs and scale. Take
care not to scrape the cylinder walls when moving the
pistons.
Solenoid Valves TVC and TVO (Electra–Saver only)
– These valves control the position of the turn valve in
response to signals from the “AUTO SENTRY” control-
ler. With both valves de–energized, equal pressure is
applied to both ends of the actuator to hold it in its pres-
ent position. If TVC only is energized, the right side of
the turn valve actuator is exhausted to the compressor
inlet cavity, causing the turn valve to move towards the
full load position. If TVO only is energized, the left end
of the turn valve actuator is exhausted to the compres-
sor inlet cavity, causing the turn valve to move towards
the unload position. See “Auto Sentry Operation” in
Controller Manual 13–9/10–647, for a description of
how the turn valve position is controlled during normal
operation.
System Pressure Transducer – This transducer is
connected after the minimum pressure valve. It con-
verts the pressure in the plant air system into an electri-
cal signal for use by the “Auto Sentry” controller for
modulation and control.
Reservoir Pressure Transducer – This transducer
is connected to the coolant system. Its signal is used
to prevent loaded starts, monitor reservoir pressure,
and monitor the condition of the air/oil separator.
Air Filter Vacuum Switch – This switch is used to
monitor air filter condition and alert the user if the filter
requires service or replacement.
Discharge Thermistor – This sensor is located di-
rectly in the compressor discharge. Its signal is used
to monitor compressor temperature and shut down the
compressor if a coolant problem is detected.
Reservoir Thermistor – This sensor is located near
the separator and is used to monitor temperature and
shut down the compressor if high temperatures are de-
tected.
Emergency Stop Push–Button – This is a main-
tained push–button, and removes power from the con-
troller outputs regardless of controller status. It is lo-
cated on the upper section of the panel, next to the
keypad. This should be used for emergency purposes
only – use the keypad [STOP/RESET] for normal con-
trolled stopping.
Automatic restarting or electrical
shock can cause injury or death.
Open, tag and lockout main discon-
nect and any other circuits before
servicing the unit.
Vibration Switch – The “Auto Sentry” controller has
one additional input available for dealer or user
installed optional shutdown switches. The switch is
simply wired in place of the jumper between terminals
7 and 9 of the terminal strip. If the contact is opened,
the compressor will be shut down, and will display
“SHUTDOWN – HIGH VIBRATION”.
The vibration shutdown switch is to be mounted on the
compressor coupling cover, and detects an increase in
vibration that could be an indication of impending dam-
age to the unit. The switch actuates when the selected
level of vibration is exceeded.
The switch must be adjusted when the unit is first
installed. Refer to the switch manufacturer’s instruc-
tion manual for complete details.
Control Transformer – This control device changes
the incoming power voltage to 110–120 volts for use by
all unit control devices. The transformers employed
are usually connectable for several input voltages, re-
fer to the transformer label for connection prior to ener-
gizing. Two primary and one secondary fuse are pro-
vided. Refer to adjacent labeling for replacement
information.
Terminal Strip – This provides connections for all
110–120 volt devices not contained within the enclo-
sure.
Fan Starter – The starter is used to provide control
and overload protection for the cooling fan or the ven-
tilation fan of water–cooled units with enclosure. Over-
load heaters should be selected and adjusted based on
the motor nameplate amps and the instructions located
inside the cover of the electrical enclosure. Three
fuses are provided. Refer to adjacent labeling for re-
placement information.
Main Starter – This starter is used to provide control
and overload protection for the main drive motor. Full
voltage starters employ a single contactor, overload
heaters should be selected and adjusted based on the
motor nameplate amps and the instructions located in-
