OPERATION AND MAINTENANCE MANUAL
Wall Mounted 0121…0661
30 (32)
Monobloc Wall Mounted Unit - WMA/WMF 0121-0181-0251-0281-0331-0551-0661 - Rev. 2.0. - Date: 18-07-2000 EN
FREE COOLING SYSTEM
PROBLEM
POSSIBLE CAUSE
CHECK/REMEDY
FREE-COOLING CYCLE DOES NOT
START
A) The servomotor damper doesn’t work.
Check the electrical of the and if it is necessary to
replace or repare the motor.
B) Control system setting is not correct.
Check the setting of the control system.
C) The control system doesn’t work.
Check the functioning of the sensors.
Cfr. mP20/W instruction manual.
D) the main board does not receive consent
of free-cooling (only units with external
control system
CDC
).
Check that the connection of external consent is
correct (cfr. par.ELECTRICAL CONNECTIONS)
ROOM TEMPERATURE IS TOO HIGH
(the high room temperature threshold alarm
is switched on)
The free-cooling damper is open on the
outside; hot and/or humid outside air flows
through the evaporator.
1) The damper motor doesn’t work; manually set
the damper in the recirculating position to await
replacement or repair. 2) the minimum set
opening of the damper is excessive; recalibrate
the minimum openingritarare (
Cfr. mP20/W
instruction manual
);
3) the main board receives a wrong command of
damper opening (only units with external
control systems
CDC
).
ROOM TEMPERATURE IS TOO LOW
(the low room temperature threshold alarm is
switched on
.)
A) The free-cooling damper is open on the
outside; cold outside air flows through the
evaporator.
see ROOM TEMPERATURE IS TOO HIGH
B) The modulation of the damper does not
work correctly with outside air that is too
cold.
1) The setting of the control system is not correct:
check the setting of the control system.
2) the base board receives a wrong command of
damper opening
(
only units with external
control systems
CDC
).
ROOM HUMIDITY IS TOO HIGH
(high room humidity threshold alarm is
switched on
)
The free-cooling damper is open on the
outside; hot and/or humid outside air flows
through the evaporator.
See “ROOM TEMPERATURE IS TOO HIGH”
HIGH COMPRESSOR CHARGE
PRESSURE
The free-cooling damper is open on the
outside; hot and/or humid outside air flows
through the evaporator.
See "ROOM TEMPERATURE IS TOO HIGH"
LOW COMPRESSOR CHARGE
PRESSURE
(formation of frost in the coil)
The free-cooling damper is open on the
outside; hot and/or humid outside air flows
through the evaporator.
see "ROOM TEMPERATURE IS TOO HIGH"
