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Vertiv / Precision air conditioning

Liebert DME12 Equipment information & support

The Vertiv Liebert DME12 is a mission-critical small room precision air conditioning indoor system delivering 12.5kW total cooling with an ultra-high sensible heat ratio for 24/7 computer rooms.

Equipment information

Brand
Vertiv
Equipment model
Liebert DME12
Equipment type
Precision air conditioning
Controller / software version
Confirm against the installed equipment
View full product specifications
Liebert DME12 Official Product View 2

Information below comes from the current product catalogue. Confirm the controller, software version and configuration of the installed equipment separately.

Rated Cooling Capacity
12.5 kW
Sensible Heat Ratio (SHF)
> 0.90
Airflow Volume
3300 m³/h
Grid Power Supply System
380VAC ± 10% (3-Phase 5-Wire 50Hz)
Refrigerant Type
R410A Eco Refrigerant
Physical Dimensions Spec
1750 × 600 × 500 mm

Alarms & troubleshooting

HP_ALM (High Discharge Pressure Alarm)
Red Alarm LED solid on, buzzer sounding, compressor locked out
Outdoor condenser coil severely fouled; outdoor condenser fan failed or unpowered; condenser airflow blocked; excessive refrigerant charge; high-pressure switch defective or wiring open.
1. Inspect and clean the outdoor condenser coil with low-pressure water or fin cleaner; 2. Verify power supply and speed control output to outdoor fan; test fan capacitor and motor winding resistance; 3. Attach refrigerant manifold gauges to measure discharge pressure; check for non-condensable gases or recover excess charge; 4. Check high-pressure switch contacts (<0.1Ω nominal); press manual reset button after pressure normalizes and restart system.
LP_ALM (Low Suction Pressure Alarm)
Amber Warning LED blinking, transitions to Red Alarm LED solid on after delay and stops cooling
Refrigerant piping leakage; indoor return air filter clogged causing evaporator coil icing; thermal expansion valve (TXV) bulb charge lost or orifice restricted; liquid line filter drier blocked; low-pressure switch malfunction.
1. Inspect indoor return air filters and evaporator coil; defrost coil and clean/replace filters if restricted; 2. Observe liquid line sight glass for continuous bubbling; perform leak detection using electronic sniffer on all joints and valves; 3. Check temperature drop across the liquid line filter-drier; replace drier if delta-T exceeds 1.5°C; 4. Attach gauge manifold to measure suction pressure and superheat; adjust/replace expansion valve and recharge refrigerant per nameplate specs.
AIR_LOSS (Loss of Airflow Alarm)
Red Alarm LED solid on, electric heater, humidifier, and compressor interlocked off
Indoor EC/centrifugal fan thermal overload tripped or run capacitor failed; differential pressure switch tubing disconnected, clogged, or switch contact defective; return air inlet obstructed; blower contactor failed or phase loss.
1. Verify indoor blower AC voltage, check capacitor rating, and test motor winding continuity and isolation to ground; 2. Inspect high/low pressure sensing tubes of the airflow differential pressure switch for kinks, dust, or detachment; 3. Manually test continuity across differential pressure switch terminals when fan is running; verify actuation threshold with a digital manometer; 4. Inspect blower motor contactor and controller digital input wiring; reset thermal overload and initiate test run.
WATER_HIGH (Condensate High Water Alarm)
Amber Warning LED blinking, cooling and humidification interlocked off
Condensate drain line clogged by sediment/algae; condensate drain pump failed or lost power; float liquid level switch mechanically jammed in upper position by scale; insufficient drain piping slope.
1. Inspect and clear the drain pan basin, clean p-trap and flush external condensate drainage lines; 2. Inspect float switch mechanical movement; clean mineral deposits and verify contact continuity across open/closed states using a multimeter; 3. If equipped with a condensate pump, verify pump power input, clean pump internal reservoir, and test manual purge operation; 4. Clear alarm on display controller and verify proper water drainage during active cooling cycle.
COMM_FAIL (T/H Sensor Communication Failure Alarm)
Amber Warning LED solid on, LCD shows communication loss, unit defaults to failsafe mode
Return air T/H sensor RS485 communication lines loose, disconnected, or reversed polarity; DC auxiliary power supply (+12V/+24V) to sensor failed; incorrect RS485 bus termination/address dip switch setting; sensor transceiver chip damaged by surge.
1. Inspect the 4-wire shielded cable between controller and return air T/H sensor; verify tight terminal connections for A(+), B(-), and power; 2. Measure DC voltage across sensor V+ and GND terminals using a multimeter (expect 12V to 24V DC); 3. Verify DIP switch address and baud rate settings on sensor backplate match controller menu specifications; 4. If wiring and power are nominal but communication LED (RX/TX) remains dead, replace the T/H sensor assembly.

Access Complete Maintenance & Full Alarm Troubleshooting Manual

This page lists high-frequency critical alarm codes commonly encountered in field maintenance. Comprehensive manufacturer troubleshooting matrices, board-level repair guides, detailed electrical schematics, and firmware commissioning manuals are delivered alongside equipment upon formal project procurement, accompanied by dedicated FAE technical support.

Contact Account Manager for Full Manual

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