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FORM 150.40-NM20
17
YORK INTERNATIONAL
SYSTEM SAFETIES
SHUTDOWN SAFETY CONTROLS
A. These software controls in the Micro Board automati-
cally reset and allow restart of the system without
operator intervention (auto-restart) when the condi-
tion causing the shutdown clears. After the condition
causing the shutdown 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. An “F” code will be displayed for
LAT* and HAT* shutdowns. Otherwise, no code will
be displayed other than one indicating the anti-recycle
timer(s) is in effect.
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 ap-
plied. 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-
tacts. Upon opening of the contacts, the unit will shut
down and will remain off until the contacts close.
Remote 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.
3. Low Pressure Cutout: Compressor suction pres-
sure cutout is a factory adjustable setpoint (R26) on
the Analog Board. It will be factory set at 44 PSIG. If
Glycol or Brine is utilized, then the cutout can be var-
ied according to mixture. Suction pressure must be
80% cutout after 30 sec. of running and must remain
above cutout after 4 minutes of operation. The sys-
tem will restart after an LP shutdown provided the
anti-recycle timer has timed out and a minimum 2
minute delay before restart has passed.
NOTE: The system will be locked out on a Fault if cycled
on LP on 3 successive starts. See LEP (Low
Evaporator Pressure Cutout) in the MANUAL
RESET SAFETY CONTROLS section.
4. Low Ambient Temperature Cutout (LAT*): Unit is
locked out when the ambient temperature is below
0° to 50°F (Adjustable on Analog Board resistor R24).
This is factory set at 35°F. Upon a rise in tempera-
ture above setpoint, the unit will restart provided the
anti-recycle timer has timed out and a minimum
2-minute delay has passed. An “F 10” code will be
displayed while the temperature is low and the sys-
tem will be shut down. The “F” will disappear when
temp. rises above cut-out.
5. High Ambient Temperature Cutout (HAT*): Unit locks
out when the ambient temperature is above 130°F.
Upon a decrease in temperature below 130°F, 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 displayed while the temperature is
high and the system will be shut down. The “F” will
disappear when temp. drops below cut-out.
MANUAL RESET SAFETY CONTROLS
A. The system will shut down instantly when a Manual
Reset Fault is sensed, but it will allow automatic re-
start until it sees a total of any 3 Faults in a 90-minute
period.**A 90-minute counter is started as soon as
the first Fault occurs. If 2 more faults do not occur in
the next 90 minutes, the counter is reset to “0”.
After a fault, restart cannot be expected until the anti-re-
cycle timers time out. No display (“F” Code) will be indi-
cated during the first two faults except for a letter code
telling the operator the anti-recycle timer is in effect.
After 3 faults, an “F” code will be displayed and the
system will not restart. The fault can be cleared and the
compressor restarted by placing the System Off/On
Switch to the OFF position. However another fault will
shut down the system and an “F” code will be displayed.
The system will continue to shut down after restart on
every Fault with an “F” Code until the system runs with-
out faulting for 90 minutes or until power is cycled. Re-
cycling power will reset the counter to “0”.
1. HP: Unit shuts down when the discharge pressure
exceeds the pressure cutout setpoint of 395 PSI set
in software. An “F4” will appear for this safety. See
also Note 6) FS (Fault Stop) for external HP safety.
2. Power Fault: Analog signals are provided to the Micro-
Board by the Motor Current Board (MCB) which gets
info from 3 current transformers (C.T.’s). A signal of
4VDC = 100% FLA Current. The system shuts down
if the signal is <1.2VDC (<30% FLA) or 4.6 VDC
(>115% FLA) when Run Time > 4 sec. This protection
assures that both contactors are energized, all C.T.’s
are connected and operating, and that the motor is
not drawing excessive current. An F1 will be displayed
for this safety. NOTE: See also Note 6) FS (Fault Stop).
3. Oil Pressure Cutout: An analog signal is provided
which is the Differential Oil Pressure (PSID). This
PSID provided to the Micro Board = Oil Pressure
PSIG - Suction Pressure PSIG. The system shuts
down if < 10 PSID at run time 4 - 30 seconds; if <25
PSID at run time 30 seconds - 4 minutes; or if <20
PSID at run time > 4 minutes. An “F2” will be dis-
played for this cut-out.
(YCAH100)
* These controls are not furnished as part of the standard unit. A
10K ohm resistor is used in place of them.
** This does not apply to item #4 (LWT Freeze Safety). A fault on
the LWT Freeze Safety will cause the system to shut down and
lock out on a single fault.