Humidity Level; Temperature; Humidifier Problem Alarm; High Water Alarm - Liebert Mini-Mate2 MMD24E User Manual

Air-Cooled Systems
Check for power shut off to the condensing unit, condenser fans not working, defective head pressure
control valves, closed service valves, dirty condenser coils or crimped lines. Also, make sure that when
the compressor contactor is energized, the side switch on the contactor closes to energize the control
circuit on the condensing unit.
Water/Glycol/ Systems
Check water regulating valves. Verify water/glycol flow (i.e., pumps operating and service valves
open). Is water tower or drycooler operating? Is the coolant temperature entering the condenser at or
below design conditions? Is AUX relay (terminals 70 & 71) operating during cooling to turn on the
drycooler?
8.1.3

Humidity Level

The humidity level alarm may be activated under the following conditions:
• High: The room return air humidity exceeds the pre-set high humidity alarm set point. Is the
unit set up for dehumidification? Check DIP switch.
• Low: The room return air humidity decreases to the high humidity alarm set point. Is the unit set
up for humidification? Check DIP switch.
• High and Low Humidity (simultaneously): The simultaneous display of two alarms results in
loss of the humidity input signal. DASHES WILL BE DISPLAYED IN THE HUMIDITY
READING DISPLAY Under these conditions, the control system deactivates both humidification
and dehumidification. Check for a disconnected cable or failed sensor.
8.1.4

Temperature

The temperature level alarm may be activated under the following conditions:
• High: The room return air temperature increases to the high temperature alarm set point. Check
for proper set point value. Is the room load more than the unit can handle (i.e., capacity too
small)? Make sure cooling components are operating (compressor or valves).
• Low: The room return air temperature decreases to the low temperature alarm set point. Check
for proper set point value. Make sure all heating components are operating (e.g., contactors,
reheats, etc.). Are reheats drawing the proper current (refer to amp rating on nameplate).
• High and Low (simultaneously): The simultaneous display of these two alarms results in loss
of the temperature input signal (or the humidity is out of sensor range: 15 to 85% RH). Dashes
will be displayed for the temperature reading. The control system will initiate 100% cooling.
Check for a disconnected cable or a failed sensor.
8.1.5

Humidifier Problem Alarm

The Humidifier Problem Alarm will sound and display a message if any of the following humidifier
conditions occur: overcurrent detection; fill system fault or end of cylinder life.
Check fault indicator LED on the humidifier control board:
• Constant LED on = Overcurrent
• 1 second LED Flash = Fill System
• 1/2 second LED Flash = Replace Tank
8.1.6

High Water Alarm

A float switch in the evaporator pan will shutdown the evaporator on a high water level. Clear the
drain and reset power to the unit in order to clear the alarm.
8.1.7

Loss of Power

The Loss of Power Alarm will activate (after power is restored to the unit) if the unit has lost power or
the disconnect switch was incorrectly turned off before the unit On/Off switch was pressed. A Liebert
remote monitoring unit (optional) will immediately indicate loss of power.
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Alarms
® ™
Liebert Mini-Mate2