10.1.4 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.
10.1.5 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 humidifier control board:
• Constant LED on = Overcurrent
• 1 second LED Flash = Fill System
• 1/2 second LED Flash = Replace Tank
10.1.6 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.
10.1.7 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.
10.1.8 Short Cycle
A Short Cycle Alarm will occur if the compressor system has exceeded 10 cooling start attempts in a one-
hour period. This can be caused by low refrigerant level or room cooling load is small compared to
capacity of the unit. Check for leaks, crimped lines and defective components. If room load is low, increase
temperature sensitivity to reduce cycle.
10.2 Optional/Custom Alarms
10.2.1 Change Filter
Periodically, the return air filters in the evaporator must be changed. The Change Filter alarm notifies the
user that filter replacement is necessary. A differential air pressure switch closes when the pressure drop
across the filters becomes excessive. The switch is adjustable using the procedure on the switch label.
Vertiv | Liebert Mini-Mate2—5 ton User Manual| 73
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