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Vertiv Liebert DM Series - User Manual

Vertiv Liebert DM Series
134 pages
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Liebert® DM
User Manual
Precision Air Conditioning

Table of Contents

Questions and Answers

  • L
    Linda GarzaAug 18, 2025
    How to troubleshoot a Vertiv Air Conditioner that does not start?
    • A
      Amber Berger DVMAug 18, 2025
      If your Vertiv Air Conditioner doesn't start, there are several potential causes. First, ensure the unit is receiving power by checking the input voltage. If there is no power, check the circuit breaker that controls the voltage at the transformer, and reset it if it's open after locating any short circuits. Another cause may be a closed float switch relay due to a high water level in the condensate pump sump; inspect the drain pipes and the condensate pump for clogs or damage. Finally, verify that the jumping cables on the control board are correctly in place.
  • M
    Michael JohnsonAug 21, 2025
    Why is my Vertiv Air Conditioner not cooling?
    • F
      ffieldsAug 21, 2025
      If your Vertiv Air Conditioner is not cooling, several issues could be the cause. Check if the compressor contactor is pulling in by testing for 24Vac ± 2Vac at the winding. If the voltage is correct, inspect the contactor itself. A plugged strainer can also prevent cooling, so clean or replace it. Lastly, a low refrigerant charge could be the culprit; use a suction and discharge pressure gauge to check the pressure and look for evident bubbles through the sight glass.
  • D
    Dylan RuizAug 22, 2025
    What to do if my Vertiv Liebert DM shows a high-pressure alarm?
    • S
      Sarah ColemanAug 23, 2025
      If your Vertiv Air Conditioner displays a high-pressure alarm, it could be due to insufficient airflow across the condenser. Remove any debris from the coil surface and air inlet. Also, check the control board for the fan speed regulation performance. Another possible cause is a condenser fan that isn't operating. Ensure that the cable connection from the control board to the terminal block of the outdoor unit is tight, that the outdoor unit connections are secure, and that the condensate pressure sensor is working normally.
  • S
    samuel07Aug 26, 2025
    Why does the heater on my Vertiv Liebert DM Air Conditioner not operate?
    • B
      Brett MeyerAug 26, 2025
      If the heater in your Vertiv Air Conditioner is not working, first verify that the heat function is enabled in the Select Options menu. If it is already on, check if there is a heat demand output from the control system by adjusting the temperature setpoint and sensitivity within the required range. If the problem persists, turn off the power and use a multimeter to check the element resistance, as the elements may be burned out.
  • K
    Kristen JonesAug 27, 2025
    What causes low pressure in a Vertiv Liebert DM?
    • T
      thompsonkathrynAug 27, 2025
      If your Vertiv Air Conditioner indicates low pressure, it may be due to refrigerant leakage. Check for the leaking place and re-charge.
  • L
    lindalopezAug 30, 2025
    How to fix an abnormal display on a Vertiv Air Conditioner?
    • G
      Gabriel WilliamsAug 30, 2025
      If the display on your Vertiv Air Conditioner is abnormal, it might be due to static discharge. Try disconnecting the system power and then restarting it. If that doesn't work, the issue could be a loose connection between the display board and the control board. Power off the unit, tighten the connection, and then restart.
  • J
    Joseph MosleySep 1, 2025
    What to do if the Vertiv Liebert DM display is off, but the equipment operates normally?
    • A
      Amy BirdSep 1, 2025
      If your Vertiv Air Conditioner has no display and the control buttons do not respond, but the equipment operates normally, it could be due to a disconnection between the display board and the control board. Check the connection between these boards. Alternatively, the display board itself may be faulty and need replacement.
  • J
    Jennifer MoodySep 3, 2025
    Why is there no display and output on my Vertiv Liebert DM?
    • R
      Rachel BakerSep 3, 2025
      If your Vertiv Air Conditioner has no display, the control buttons do not respond, and the equipment has no output, it could be caused by low power voltage. Check for proper power voltage. Another possible reason is interrupted communication between the control board and the display board, so check the connection between these boards.
  • N
    Nicole HudsonSep 5, 2025
    What causes a high-temperature alarm on a Vertiv Liebert DM Air Conditioner?
    • J
      Jason RichardsonSep 6, 2025
      If your Vertiv Air Conditioner is showing a high-temperature alarm, it could be because the high-temperature setpoint is unreasonable. Reset the setpoint. Another possibility is that the room load exceeds the unit's design ability, so check for room seal issues or consider capacity expansion.
  • D
    dennisreedSep 8, 2025
    What causes a low temperature alarm on a Vertiv Liebert DM?
    • R
      rhondabrockSep 8, 2025
      If your Vertiv Air Conditioner is showing a low temperature alarm, it could be because the low-temperature setpoint is unreasonable. Reset the setpoint. Another possible cause is improper heater operation current, so check for proper heater working operation.

Summary

Safety Precautions and Measures

Chapter 1: Overview

Chapter 2: Mechanical Installation

2.1. Unpacking and Inspection

Procedures for unpacking and inspecting the unit upon arrival.

2.3. System Installation Arrangement

Details on system arrangement and installation modes for indoor/outdoor units.

2.5. Installing Indoor Unit

Requirements and procedures for installing the indoor unit.

2.6. Installing Outdoor Unit

Installation notes, procedures, and piping connection principles for the outdoor unit.

2.8. Charging Refrigerant

Detailed procedures for charging refrigerant, including long piping systems.

2.9. Installation Inspection

Checklist for verifying successful mechanical installation implementation.

Chapter 3: Electrical Installation

3.3. Indoor Unit Power Cable Connection

Procedure for connecting the power supply cables to the indoor unit.

3.4. Connecting Power Cable of Outdoor Unit

Procedure for connecting the power supply cables to the outdoor unit.

Chapter 4: Start-up Commissioning

4.1. Start-Up Inspection

Inspection of unit components before commissioning for proper operation.

4.2. Function Testing

Testing the cooling, heating, humidifying, and dehumidifying functions.

Chapter 5: Microprocessor Controller

Chapter 6: Outdoor Fan Speed Controller (Only for 22 kW;27 kW)

Chapter 7: System Operation and Maintenance

Vertiv Liebert DM Series Specifications

General IconGeneral
RefrigerantR410A
Dimensions (HxWxD)Varies by model
WeightVaries by model
Airflow ConfigurationDownflow, Upflow
Power Supply460V, 50/60Hz
Humidity Range20% - 80% RH (non-condensing)
AirflowVaries by model
Noise LevelVaries by model
ComplianceUL, CE

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