Troubleshooting; Table 31 Troubleshooting - Liebert Mini-Mate2 MMD24E User Manual

11.0 T
ROUBLESHOOTING
Table 31

Troubleshooting

Symptom
No power to unit
Control voltage circuit
breaker (at transformer)
open
Float switch relay has
Unit will not start
closed due to high water
in the condensate pan.
Jumper not in place
"Cooling" is not displayed
at the control panel.
Short cycle prevention
control.
Compressor contactor
not pulling in.
No cooling
Compressor high head
pressure.
Plugged filter/drier.
Low refrigerant charge.
Insufficient air flow across
condenser coil
Water/Glycol-cooled only:
Compressor high No fluid flowing through
head pressure condenser.
Self-Contained, Air-
Cooled only: Condenser
fan not operating
DIP switch not set to
enable humidifier option
"HUMIDIFY" not
displayed at control panel
Defective board
Humidifier does not
operate
Failed humidity sensor
No water flow
Canister fill rate is not
keeping up with the
steam output.
Possible Cause
Check voltage at input terminal block.
Locate short and reset circuit breaker.
Has rubber band been removed from float switch? Check drain and line.
Access from bottom through discharge air gills. Power must be cycled at
the disconnect to reset.
Check terminal TB1-4 and TB1-5 for jumper or N/C contact. Check pins
1-8 and 1-9 for jumper, or N/C high temperature sensor contact. Check
pins 5-4 and 5-5 for jumper or N/C smoke detector contact.
Adjust TEMP control setpoint and sensitivity to require cooling.
Control software delays compressor 3 minutes cooling, from stop to start
Check for 24 VAC ± 2 VAC at terminals P4-8 and P4-4. If voltage, check
contactor. If no voltage at P4-8 and P4-4, check at terminals P2-3 and
P2-8. If voltage, check freezestat.
See below for cause.
Replace filter/dryer.
Check pressure gauges. See Table 11 and Table 13 for recommended
pressures. At low ambient temperatures, proper refrigerant charge is
very important on units with Lee-Temp receivers.
Remove debris from coil and air inlets.
Check fluid supply to regulating valve. Adjust valve if necessary.
Check fan operation.
See DIP switch setting Table 30.
Increase humidity control setpoint and sensitivity to require
humidification.
Check voltage at P3-1 and P1-9 on interface board for 24VAC ± 2VAC. If
no voltage, check wiring and/or replace board. Check wiring from control
panel to board.
Humidity display will indicate dashes. Check wiring from
temperature/humidity board to the control board and from the wall box to
the control board. Replace wall box or temperature/humidity circuit board
(if remote).
Make sure switch is in Run position. Check humidifier water supply
(including filter screen) and check nylon overflow line if canister is full.
Check fill valve screen opening and capillary tube for obstructions.
Check water supply pressure (minimum 10 PSIG).
Check Or Remedy
69
Troubleshooting
® ™
Liebert Mini-Mate2