FORM 150.66-NM3
ISSUE DATE: 09/25/2020
105
JOHNSON CONTROLS
SECTION 7 - UNIT CONTROLS
7
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 3
seconds to cause a system shutdown. The safety locks
out a system after the first fault and will not allow au
-
tomatic restarting.
Unit Safeties
Unit safeties are faults that cause all running compres-
sors 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.
U N I T F A U L T :
L O W A M B I E N T T E M P
The Low Ambient Temp Cutout is a safety shutdown
designed to protect the chiller from operating in a low
ambient condition. If the outdoor ambient temperature
falls below the programmable cutout, the chiller will
shut down. Restart can occur when temperature rises
2°F above the cutoff.
U N I T F A U L T :
L O W L I Q U I D T E M P
The Low Leaving Chilled Liquid Temp Cutout protects
the chiller form an evaporator freeze-up should the
chilled liquid temperature drop below the freeze point.
This situation could occur under low flow conditions or
if the micro panel setpoint values are improperly pro-
grammed. Anytime the leaving chilled liquid tempera-
ture (water or glycol) drops below the cutout point, the
chiller will shutdown. Restart can occur when chilled
liquid temperature rises 2°F above the cutout.
U
N I T F A U L T :
1 1 5 V A C U N D E R V O L T A G E
The Under Voltage Safety ensures that the system is
not operated at voltages where malfunction of the mi-
croprocessor could result in system damage. When
the 115 VAC to the micro panel drops below a certain
level, a unit fault is initiated to safely shut down the
unit. Restart is allowed after the unit is fully powered
again and the anti-recycle timers have finished count
-
ing down.
U N I T F A U L T :
H I G H M T R C U R R
When the CURRENT FEEDBACK ONE PER UNIT
option is selected under the OPTIONS key, the unit will
shut down when the voltage exceeds the programmed
trip voltage for 5 seconds.
The trip voltage is programmed at the factory accord-
ing to compressor or unit RLA.
Restart will occur after the anti-recycle timer times
out.
Unit Warning
The following messages are not unit safeties and will
not be logged to the history buffer. They are
unit warn-
ings
and will not auto-restart. Operator intervention is
required to allow a restart of the chiller.
! ! L O W B A T T E R Y ! !
C H E C K P R O G / S E T P / O P T N
The Low Battery Warning can only occur at unit pow-
er-up. On micro panel power-up, the RTC battery is
checked. If a low battery is found, all programmed
setpoints, program values, options, time, schedule, and
history buffers will be lost. These values will all be re
-
set to their default values which may not be the desired
operating values. Once a faulty battery is detected, the
unit will be prevented from running until the PRO-
GRAM key is pressed. Once PROGRAM is pressed
the anti-recycle timers will be set to the programmed
anti-recycle time to allow the operator time to check
setpoints, and if necessary, reprogram programmable
values and options.
If a low battery is detected, it should be replaced as
soon as possible. The programmed values will all be
lost and the unit will be prevented from running on the
next power interruption. The RTC/battery (031-02565-
000) is located at U5 on the IPU microboard (031-
02630-000).
I N C O R R E C T
U N I T T Y P E
This indicates the condensing unit jumper is installed
between J4-11 and J4-6, on a liquid chiller. This jumper
must be removed to operate the chiller.
Summary of Contents for YCAL Series
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