Alarms
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 and 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?
8.1.3Humidity Level
The humidity level alarm may be activated under the following conditions:
•High: The room return air humidity exceeds the
•Low: The room return air humidity decreases to the low humidity alarm set point. Is the unit setup 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.
NOTE
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?
8.1.4Temperature
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
8.1.5Humidifier 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
8.1.6High 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.
53 | Liebert® |
