22
YORK INTERNATIONAL
SINGLE CIRCUIT UNITS
F4 Fault
High Discharge Pressure
An analog signal is sent to the Analog Input Board and
from there to the Micro Board by the Discharge Pres-
sure Transducer. The unit shuts down when the dis-
charge pressure exceeds the pressure cutout setpoint
of 395 PSI (2721 kPa) set in software. An F4 will appear
for this safety. Normally the manual H.P. cut-out (pri-
mary safety) will open before this safety (back-up safety)
is activated causing an F1 Fault.
AUTOMATIC RESET FAULTS
The unit will shut down instantly and display an “F” code
when an Automatic Reset Fault is sensed. The compres-
sor will automatically restart, if load demands, when the
condition causing the shutdown clears.
F9 Fault
High Ambient Temperature (HAT)
The unit will shut down when the ambient temperature
is above 130°F (54.4°C). Upon a decrease in tempera-
ture below 130°F (54.4°C), the unit will restart providing
the anti-recycle timer has timed out and a minimum
2-minute delay has passed. An “F9” code will be dis-
played while the temperature is high. The F will auto-
matically disappear when temperature drops below
cut-out.
F10 Fault
Low Ambient Temperature (LAT)
The unit shuts down when the ambient temperature is
below 0° to 50°F (–17.8°C to 10°C) (This is an adjust-
able cut-out, adjustable on the Combo Board resistor
R1). This is factory set at 35°F (1.7°C). Upon a rise in
temperature above setpoint, the unit will restart provided
the anti-recycle timer has timed out and a minimum 2
minute delay has passed. An “F10” code will be displayed
while the temperature is low. The F will automatically
disappear when the temperature rises above cut-out.
MANUAL RESET FAULT (1 FAULT and
LOCKOUT)
This type safety is applicable to the Low Leaving Water
Temperature Safety. The unit will shut down and lock
out when this fault is sensed.
F11 Fault
Low Leaving Water Temperature (LWT)
An analog signal is sent by the Leaving Chilled Water
Sensor to the Analog Board and then to the Micro. If the
temperature drops below the freeze point as set by R2
on the Combo Board, the unit shuts down. Typically with
water, the LWT cut-out is set at 36°F (2.2°C) (factory
setpoint). For Brine applications, the setpoint can be
varied from 0°F (-17.8°C) to 40°F (4.4°C) on the Combo
Board by adjusting R2. An F11 code will appear for this
safety.
AUTOMATIC RESET SAFETIES
Shutdown Safety Controls
A. These software safety controls in the Micro Board im-
mediately shut the unit down and automatically reset
allowing restart of the system, without operator inter-
vention (auto-restart), when the condition causing the
shutdown clears. After the condition causing the shut-
down clears, the unit will restart in a minimum of 2
minutes, or a maximum of 10 minutes, depending
upon the remaining time on the anti-recycle timer.
Restart will occur only if cooling demand is present.
1. Power Failure: After power has been restored, the
unit will automatically restart after a 2 minute time
delay. System acts as it does any time power is
applied. Restart is dependent on cooling demand
after the 2 minute start-up timer has completed its
cycle.
2. Flow Switch/Remote Cycling Device: The Micro
Board monitors the closure of the Flow Switch Con-
tact to assure that water flow is present in the evapo-
rator. The Micro Board senses the Flow Switch in-
put to the R.P. Relay whose contacts connect to
J19 of the Combo Board. If the Flow Switch opens,
an “A” code will be displayed and the unit will shut
down and will not restart until flow is present. The
Flow Switch is connected to terminals 3 & 4 of the
terminal block (TB5) at the lower left of the Power
Panel. (See Fig. 9.)
Remote EMS/BAS/Time Clock devices are wired in
series with the Flow Switch and can be used to start
and stop the unit. Anytime the contacts open, an
“A” Code will appear on the display indicating a Flow
Switch problem or an EMS/BAS/Time Clock stop.
OTHER SAFETY CONTROLS
1. Suction Pressure: If the Suction Pressure exceeds
105 PSIG (723 kPaG), the Micro Board will not allow
loading or will unload the compressor. It will automati-
cally allow reloading when suction pressure drops be-
low 95 PSIG (654 kPaG). Since high suction pres-
sure relates to high discharge pressure, this feature
reduces the chance of faulting on high discharge pres-
sure by unloading or inhibiting loading which reduces
the discharge pressure.
2. Discharge Pressure: If Discharge Pressure exceeds
390 PSIG (2687 kPaG), the Micro Board will not al-
low loading or will unload the compressor. It will auto-
F
4
F
9
F
0
1
F
1
1