York YCAL0014E Series Installation Operation & Maintenance page 86

UNIT CONTROLS
The compressor is also equipped with a discharge
temperature sensor for the purpose of sensing internal
scroll temperature. This sensor protects the scrolls
from overheating due to inadequate cooling that may
occur when refrigerant charge is low, or superheat is
too high.
When the sensor senses a high temperature, it opens the
motor protector circuit in the compressor causing the
compressor to shut down.
During the first two faults an MP/HP INHIBIT message
will be displayed and the system will not be locked out.
Only after the third fault will the MP/HP Fault message
shown below be displayed on the STATUS display.
Additionally, the system will be locked out.
S Y S 1 M P / H P C O
S Y S 2 M P / H P C O
Whenever the motor protector or discharge sensor
shuts down a compressor and the system, the internal
compressor contacts will open for a period of 30 minutes
to assure that the motor or scroll temperatures have time
to dissipate the heat and cool down.
After 30 minutes, the contacts will close and the system
will be permitted to restart. The microprocessor will
not try to restart the compressors in a system that shuts
down on this safety for a period of 30 minutes to allow
the internal compressor timer to time out.
S Y S 1 H I G H
S Y S 2 H I G H
When System Current Feedback option is selected
(Option 11 under OPTIONS key Current Feedback),
this safety will operate as follows. If the actual voltage
of the system exceeds the programmed trip voltage for
5 seconds, the system will shutdown. This fault will not
be cleared until the condition is no longer present.
S Y S 1 L O W
S Y S 2 L O W
The Low Evaporator Temperature Cutout is to protect
the evaporator from freeze-up with R-407C. This
safety uses the Cooler Inlet Refrigerant Temp Sensors
to monitor evaporator inlet refrigerant temperature
on each system. These sensors are only installed on
R‑407C units. This safety is ignored for the first 270
seconds of runtime.
86
F A U L T
F A U L T
M T R C U R R
M T R C U R R
E V A P T E M P
E V A P T E M P
In water cooling mode, if the refrigerant temperature
falls below 21°F (-6.1°C), the system will be shut
down.
In glycol cooling mode, if the refrigerant temp. is below
21°F (-6.1°C) and falls 19°F (-7.2°C) below the leaving
chilled liquid temp., the system will shut down.
In either cooling mode, if the cooler inlet refrigerant
temp. sensor reads out of range low, the system will
also shut down.
S Y S 1 L O W
S Y S 2 L O W
The Low Superheat Cutout is to protect the compressor(s)
from liquid floodback due to low suction superheat.
This safety is only active when EEV is selected as the
expansion valve in Service Mode. This safety is ignored
for the first 15 seconds of system runtime.
This safety can be triggered by two events. The first is when
suction superheat is less than 2.0°F for three seconds. The
second is when the EEV pilot solenoid is closed 10 times
in two minutes due to low superheat.
S Y S 1 S E N S O R
S Y S 2 S E N S O R
The Sensor Failure Safety prevents the system from
running when the sensors measuring superheat are not
functioning properly. This safety is only active when
EEV is selected as the expansion valve type in Service
Mode. This safety is ignored for the first 15 seconds of
system runtime.
This safety will shut down a system if either suction
temperature or suction pressure sensors read out of
range high or low. This condition must be present for
three seconds to cause a system shutdown. The safety
locks out a system after the first fault and will not allow
automatic restarting.
Unit Safeties
Unit safeties are faults that cause all running compressors
to be shut down. Unit faults are auto reset faults in that
the unit will be allowed to restart automatically after the
fault condition is no longer present.
FORM 150.62-NM8 (1020)
S U P E R H E A T
S U P E R H E A T
F A I L U R E
F A I L U R E
JOHNSON CONTROLS