Carrier CU-S 401, Use & Maintenance Instructions, Page: 11 / 24

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CAUTION
Magnetothermal safety switches should be used to protect the main power sup-
ply line from power surges.
Only qualified personnel is authorised to replace the safety thermal relays fitted
on motors.
Only qualified personnel must be authorised to make electrical connections.
6.2.2 Connection to the water mains (water condenser)
The water condenser must be connected to the water mains following the indications
on the plates next to the tubes, which are marked IN (ENTRATA) and OUT (USCI-
TA). The diameter of the pipes used to make the connection must not be smaller
than the unit’s outlet tubes. Pressure in the water circuit must be at least 1 bar.
6.3 Checks, adjustments and settings Before switching the machine on, ensure that:
- locking screws are fixed tight
- electrical connections have been made correctly
When the unit is opened, check that:
- no tools have been left inside
- assembly has been correctly performed
- there are no gas leaks
- panels have been correctly fixed.
6.4 Setting of the control and During the testing on make the setting of these devices. Below we list the rated
power devices values of the pressure switches settings; these values must be considered
approximates as size order.
Low pressure switch 0,2 bar
high pressure switch 28 bar working with R404A
T o start the machine up proceed as follows:
A) Set the control thermostat supplied by others (usually fitted on the evaporator)
to the required temperature in the cold room or cabinet. The thermostat can be
wired as per the schematic or can act directly on the liquid line solenoid valve.
B) Select 'preheating' position on the PREHEATING/STOP/RUN switch supplied
by others. Method of connection is shown in the schematic.
C) Turn the mains isolator switch to ON
Leave the unit in preheating mode for at least 4 hours in mild climates and longer
( at least 12 hours ) in cold climates. This should be repeated every time the unit
has been switched OFF for more than 24 hours. When shutting down the unit
during normal operation always leave in preheating mode.
D) Having completed the preheating phase, turn the PREHEATING/STOP/RUN
switch to the 'RUN' position.
E) If the compressor does not start check:-
- if there is mains voltage to the unit
- if the correct phase sequence has been made
Low pressure trip indicates low refrigerant charge. Check for leaks and having
repaired them, recharge the system and restart the commissioning as above.
Auxiliary fuse trip. Find and remove cause of trip.
8.1 Description of the unit Uniblock CU refrigerating units operate through a scroll refrigerating compressor,
working cycle powered by mains a/c supply (single phase or three phase) and use HFC refrige-
rating liquids.
8.2 Diagram of the unit’s Units in the CU-S range feature a special electrical system, a diagram
electrical system of which is attached to this manual.
77.. PPLLAAC CIIN NG G IIN NTTO O SSEERRVVIIC CEE O OFF TTH HEE UUN NIITT
77.. PPLLAAC CIIN NG G IIN NTTO O SSEERRVVIIC CEE O OFF TTH HEE UUN NIITT
88.. H HO OW W TTO O O OPPEERRAATTEE TTH HEE UUN NIITT
88.. H HO OW W TTO O O OPPEERRAATTEE TTH HEE UUN NIITT
ON
OFF
ON
OFF
Control Panel
CU-S unit