York YLUA0078 Installation Operation & Maintenance page 106

SECTION 7 – UNIT CONTROLS
Whenever the motor protector or discharge sensor
shuts down a compressor and the system, the inter-
nal compressor contacts will open for a period of 30
minutes to ensure that the motor or scroll temperatures
have time to dissipate the heat and cool down.
After 30 minutes, the contacts will close and the sys-
tem will be permitted to restart. The micro 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 to time out.
During the 30 minute timeout, the MP/HPCO INHIB
message will be displayed. The MP/HPCO fault will
only be displayed after 3 shutdowns in 90 minutes,
indicating the system is locked out and will not
restart.
S Y S 1 H I G H
S Y S 2 H I G H
When the System Current Feedback option is installed
and selected (Option 11 under OPTIONS Key Current
Feedback), this safety will operate as follows. If the
actual feedback voltage of the system proportional to
currents exceeds the programmed trip voltage for 5
seconds, the system will shutdown.
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
L O W A M B I E N T
The Low Ambient Temp Cutout is a safety shutdown
designed to protect the unit from operating in a low
ambient condition. If the outdoor ambient temperature
falls below the programmable cutout, the unit will shut
down. Restart can occur when temperature rises 2°F
above the cutoff.
U N I T
1 1 5 V A C U N D E R
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
106
M T R C U R R
M T R C U R R
F A U L T :
T E M P
F A U L T :
V O L T A G E
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
H I G H M T 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 pro-
grammed 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 unit.
! ! 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
This indicates the condensing unit jumper is not in-
stalled between J11-7 and J11-12, on the I/O Board.
This jumper must be installed to operate the condens-
ing unit.
FORM 150.73-NM1
ISSUE DATE: 09/04/2020
F A U L T :
C U R R
! !
T Y P E
JOHNSON CONTROLS