Manual 2100-643C
Page
26 of 59
Special Considerations
• Compressor Run Time – Once activated, the
compressor will run for a minimum of 5 minutes,
regardless of setpoint (control board programming)
• Compressor Off Time – Once deactivated, the
compressor will not start again for a minimum of 2
minutes.
• High Pressure Situation – The high pressure switch
routes through the compressor control module
(CCM), which allows one switch opening followed
by a delay (soft lockout) of at least 2 minutes
before trying again. If the switch is still open—or
opens again on the same call—the CCM locks out
the compressor and outdoor fan. Additionally, the
CCM will send 24V to the high pressure alarm
relay, which will then send a digital input to the DI
3 terminal.
• Low Pressure Situation – The low pressure switch
is connected directly to DI 4:
1. On a call for cooling, the board ignores the
low pressure switch status for 2 minutes (OAT
above 50°F) or 3 minutes (OAT below 50°F).
2. If the switch is still open, the compressor
will shut down and the controller will wait an
additional 2 minutes.
3. If the switch is still open, the controller will
notify of an alarm and lock out the compressor.
However, if the switch closes during this time,
the compressor will start again and wait for 2
minutes (OAT above 50°F) or 3 minutes (OAT
below 50°F).
4. If the low pressure switch is open at this time,
the compressor will lock out and the controller
will notify of an alarm.
• High Temperature 2 Alarm – Should the shelter
controller see 90°F, both free-cooling dampers will
open (regardless of outdoor temperature) to cool
the building.
• Smoke Alarm – Should the smoke detector send
an alarm signal to the controller, all blower,
compressor and ventilations functions cease.
• Hydrogen Alarm – Should the hydrogen detector
send an alarm signal to the controller, both
free cooling dampers will open (regardless of
temperature) to dilute the shelter air.
• Freezestat – If the coil temperature is below 30°F
for 120 seconds, the compressor will deactivate for
5 minutes, or until the sensor sees 55°F, whichever
comes first.
• Generator Run – During generator operation, the
system may limit compressor operation to only one
unit providing that a specific jumper was removed
from the LC controller terminal block and the
alarm wires were connected to a generator-run
relay (please refer to the Installation section of this
manual regarding alarms and wiring).
