Liebert CHALLENGER 3000 - Manual (Page 48)

Alarm Descriptions
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5.1.8 High Temperature and Low Temperature (Simultaneously)
If these two alarms are displayed at the same time, the temperature input signal is lost (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.
5.1.9 Humidifier Problem
Infrared Humidifiers
This alarm is activated by the high water float switch in the humidifier pan assembly. The high water
float switch is normally closed and opens upon alarm condition. Check for drain clog and, if present,
clean drain. Check for float switch stuck high; replace the switch as necessary. Check for proper oper-
ation of the humidifier water makeup valve.
Steam Generating (Canister) Humidifiers
This alarm is activated by a signal from the humidifier control indicating that the canister needs to be
replaced.
5.1.10 Loss of Air Flow
A differential air pressure switch is used to indicate loss of air flow in Challenger 3000 units.
Check for blockage of unit air outlet or inlet. Check blower motor fuses and overload reset. Check for
broken belts. Make sure blower wheels are tight to shaft. Run diagnostics to see if the fan contactor is
working properly.
5.1.11 Loss of Power
If the unit has lost power, or the disconnect switch was turned off before the unit ON switch was
pressed (to turn the unit Off), this local alarm will occur when power is restored to the unit. A Liebert
remote monitoring unit (optional) will immediately indicate loss of power.
5.1.12 Low Humidity
If the return air humidity has decreased to the Low Humidity Alarm setpoint, check to make sure
that the unit is setup for humidification (check DIP switch). Check for proper setpoints. Does the
room have a vapor barrier to seal it from outdoor humidity? Are doors or windows open to outside air?
Run diagnostics to make sure the humidifier system is working properly.
5.1.13 Low Suction Pressure
A pressure switch monitors the suction pressure at the compressor inlet to monitor whether pressure
has dropped below a factory preset point while the compressor is in cooling operation. When pressure
drops below a factory preset point, the switch opens. After the positive start kit time delay, and the
switch stays open for five minutes, the alarm is activated. The alarm stays active for 90 minutes.
Look for conditions that would cause loss of refrigerant. Check for piping problems such as leaks or
crimped lines. Check for inoperative components such as liquid line solenoid valve, low pressure
switch, expansion valve, and head pressure control valve. Check for closed service valves in the liquid
line or at the condenser or receiver.
5.1.14 Low Temperature
If the return air temperature has decreased to the Low Temperature Alarm setpoint, check for proper
setpoints. Run diagnostics to make sure all heating components are operating (contactors and
reheats). Are reheats drawing the proper current? (See nameplate for amp rating.)
5.1.15 Main Fan Overload
An optional tri-block overload is required for this alarm, and may or may not replace internal motor
overload, depending on your model. The overload device is located next to the main fan contactor in
the line voltage section. The alarm is activated when the overload is tripped.