Code Description Severity Self-Clear Latching Shutdown Shutdown
Action: Check operation of cooling valve.
A34 Leak - Unit 1 —
ü
ü (or not)
—
Detail: Level switch in cabinet drip tray has detected a substantial fluid leak. Event may be set for Alarm Only (default), or Alarm + Unit Shutdown.
Action:
A35 Leak - External 1 —
ü
ü (or not)
—
Detail:
The leak detection tape installed under the floor (if fitted – optional extra) has detected a substantial fluid leak. Alarm may be set for Alarm
Only (default), or Alarm + Unit Shutdown.
Action
Identify and repair the leak. (Note: A leak of this magnitude that does not bring up any other alarms, would most likely be from the Primary
circuit).
A36 PS1 Difference Out of Limits 3
ü
— — —
Detail:
Difference between Secondary return pressure sensors PS1a and PS1b is more than 0.2 bar (3PSI), (default) for a period of 30 seconds
(default) or more. Controller will continue to read just the higher of the 2 values.
Action: Check T2a sensors against temperature sensor resistance chart in Section 2.5 and replace if faulty.
A37 PS4 Difference Out of Limits 3z
ü
— — —
Detail:
Difference between Secondary return pressure sensors PS4a and PS4b is more than 0.2 bar (3PSI), (default) for a period of 30 seconds
(default) or more. Controller will continue to read just the higher of the 2 values.
Action: Replace sensor with the lower reading.
A38 Sec. Over Pressure 1
ü
—
ü or not
—
Detail:
Pressure at PS2 has increased above the set value of 6 bar (87PSI) (default). Alarm may be set for Alarm Only (default), or Alarm + Unit
Shutdown.
Action:
Most likely cause will be excessive heat build-up in the system, or a breach between Primary and Secondary circuits within the plate heat
exchanger. Check for High Temp alarms, check bladder in expansion vessel(s) has not ruptured, relieve pressure at drain point. Remove
heat exchanger and replace.
A39 System Low Pressure 2 —
ü
—
ü
Detail:
Pressure at PS1 has dropped more than 0.2Bar (3 psi) (set, non-adjustable) below fill pump activation threshold for more than 1 minute (set,
non-adjustable, applicable when unit is running in automatic/online mode).
Action:
Check amount of fluid in make up container and re-fill if necessary. Ensure fill pump hoses are free of air locks, container is properly
connected and fill pump is operational. Check system for leaks.
A40 Insufficient Fluid 1 —
ü ü
—
Detail:
On Initial Start-up – if level sensors are not made, fill pressure has not been achieved and fill pump has been running for more than 1 minute,
then unit will not start or shutdown immediately.
While Unit is Running – This will be in conjunction with an A41 – Level Sensor – No Fluid Detected alarm (refer to A41 for detail). If level
sensors are not made and flow or DP is < 50% of flow/DP setpoint, then unit will shutdown after a 1 second delay.
Action:
Check that water make-up container is properly connected (or filling wand is fully immersed, if used). Check system for leaks. Check there
is no trapped air in fill pump hoses and system is fully vented. Check auto air vents are open.
A41
Level Sensor – No Fluid
Detected
2 —
ü
— —
Detail:
While unit is running only – if both Level sensors are open circuit for more than 1 second then this alarm will be raised, providing flow or DP
(depending on control function set) is >50% of flow/DP setpoint. If flow/DP is below this threshold, then an A40 - Insufficient Fluid’ alarm
Table 4.41 Alarm Identification and Severity Level (continued)
56 Proprietary and Confidential ©2025 Vertiv Group Corp. 4 Operation
Vertiv™ CoolChip CDU 600 Operation and Maintenance Guide
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