Heatcraft Refrigeration Products H-IM-79D - Manual (Page 18)

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ELECTRIC DEFROST MODE
When a defrost is initiated, the EEV closes, the compressor is allowed to pumpdown and
shut off. The evaporator fans are cycled off and the defrost heaters are energized.
On multiple evaporator systems, all controllers must terminate their defrost, either on
temperature or fail-safe time, before the master controller will end the defrost cycle.
There is a 2 minute condensate drain-down period after which the compressor is started for
a refreeze period. The evaporator fan stays off (fan delay). The refreeze period will last until
the evaporator suction temperature is at 28
°
F or 3 minutes has elapsed. After this
sequence, the system is back in the refrigerating mode and evaporators fans are now
running.
AIR DEFROST MODE
The sequence is the same as for electric defrost except that there are no heaters and the
evaporator fans run continuously. If the air defrost for motors are wired through the fan
relay on the board, they will remain energized during defrost mode.
ALARMS
Beacon provides a set of dry contacts for use in signaling an alarm. These contacts can be
connected to a light, a buzzer, a bell etc., which will be activated when an alarm condition
occurs. When the Beacon II is energized, the alarm contacts are OPENED. When an
alarm condition is detected, the contacts are CLOSED.
Conditions under which the alarm contacts will close are:
• High Box Temperature – LED Display:
A 1 - Room temperature has exceeded the Alarm
High ALH value for the Alarm time ALt , programmed.
• Low Box Temperature - LED Display: A 2 - Room temperature has dropped below the
Alarm Low ALL value for the Alarm time ALt , programmed
• System Start-up failure – LED Display: A 3 - Compressor pumps down and tries to
restart after 4 minutes. After 4 unsuccessful attempts to restart, the alarm code A 3 is
displayed. System continues trying to restart.
• Input Fault – LED Display: A 4 - Box Temp., Suction Temp., Pressure Transducer open
or not installed.
• Power failure – Loss of power to the Evaporator
ALARM CODES
A 1 High Box Temp
A 2 Low Box temp
A 3 System Start-up failure Compressor pumps down and tries to restart after
4 minutes
A 4 Input Fault Box Temp., Suction Temp., Pressure
Transducer open or not installed
Defrost / Alarms
CLEARING ALARMS
Alarms A1 – High Box Temp. and A2 – Low Box Temp. will clear automatically if the Box
Temp. decreases or increases to below or above the Alarm setpoint temperature. Placing
the system in the “Service Mode” or turning off power will clear the A3 Alarm. Replacing
the Room Sensor, Suction Sensor or Pressure Transducer will clear the A4 Alarm.