Liebert Refrigerant Distribution Unit XDP - Manual (Page 37)

Troubleshooting
31
6.0 T
ROUBLESHOOTING
Table 16 Troubleshooting the XDP
Symptom Possible Cause Check or Remedy
Pump will not energize
No main power Check L1, L2 and L3 for rated voltage.
Loose electrical connections Tighten connections.
Overloads tripped Allow pump to cool. Check amp draw.
Tripped circuit breaker Check circuit breaker to pump(s).
Incorrect phase wiring See Table 5.
Pump will not run
No chilled water
Check and verify that there is supply chilled water to the
Liebert XDP.
Isolation valve(s) on pump suction
and/or discharge is closed.
Open all isolation valves completely during normal
operation.
Supply chilled water is too high
Check and verify that the chilled water temperature
setpoint is at 50°F (10°C) or lower and that there is flow
on the chilled water side.
Liebert XD cooling modules are Off
Check Liebert XD cooling module to make sure that they
are On prior to starting the Liebert XDP.
Low Refrigerant Temperature (high
dew point)
Check alarm(s) history on Liebert XDP. The Liebert XDP
was operating below the dew point for a significant
amount of time. Check humidity in conditioned space,
lower humidity if necessary to allow Liebert XDP to
operate at a lower temperature. (Disconnect must be
switched to Off then back On to allow Liebert XDP to
reset itself).
Incorrect location of
temperature-humidity sensors
Place the sensor on the RETURN AIR side of the primary
air mover (e.g., Liebert Deluxe System 3). Do not install
the sensor near unsealed doors, windows and similar
areas.
Pressure switch not making contact
Check both differential pressure settings. If not within
6 psi, ±1 psi (41kPa, ±7kPa; 0.41 bars, ±0.07bars) then
manually change accordingly.
Not enough charge See 3.0 - Checklist for Liebert XDP Startup.
Pump noisy
Cavitation due to vapor in pump
Check for adequate charge in system, refer to the User's
Manual. 3.0 - Checklist for Liebert XDP Startup
Worn motor bearings Replace pump
Liebert XDP (Pump)
suddenly stops
Low Refrigerant Temperature (High
dew point)
Check humidity of room along with location of remote
sensors. Make sure that the sensors are not located in a
cold area where there is a lack of sufficient air flow.
Clogged filter/dryer and/or impeller Clean out debris.
Pipe rattle Loose pipe connections Check pipe connections
Chilled water valve not
working
Motor operates but valve won't open
Check linkage for adjustment and be sure that it is tight on
the valve.
Actuator motors
No 24 VAC power to motor Check for 24 VAC between P2-1 and P2-4.
No signal from control Check 24 VAC at P22-1 (close) or P22-3 (open).
Motor not operating
Unplug P22 completely off of the board. Jumper P22-5 to
P2-4 for grounding, then jumper P22-1 to P2-1 to drive
close. Remove jumper to close, and then jumper P22-3 to
P2-1 to drive open. If motor fails to work, replace it.
Motor burnout
Check control panel for welded
contactor contacts or welded
overload contacts
Replace defective components.
Main 24 VAC fuse trips
Shorts or loose connections Check the wiring connections of the 24 VAC circuit.
Faulty circuit board Replace the circuit board.
Unstable pump
operation
R-134a pump loop is overcharged
While pump is running R-134a receiver level must be
within recommended levels (see Figure 21).