Removal Procedure; Components And Maintenance; Fan Motor Assembly - Carrier 42NL series Installation, Operation And Maintenance Instructions

If several units are connected to a common collector, a
device must be installed (Fig. 11). Before operating the unit,
ensure that the water flows into the internal condensate
drain pan by pouring some water into it. If problems are
detected, check the drain pipe slope and look for possible
obstructions. In all cases the connection duct(s) at the unit
outlet must be insulated to prevent any condensate
formation on the walls.
NOTE: The pressure losses of these ducts must be
compatible with the unit performance. The duct must be
as smooth as possible. Avoid sharp bends. Check that there
are no leaks or kinks, and that there is no dirt or
installation debris inside the ducts. Debris within the ducts
might damage the fan wheel and the damper in the air
diffusers.
When installation is complete - i.e. when the unit is attached
to the ceiling, air ducts are complete, water mani-folds are
in position with stop valves ready on the connection stubs,
and electrical installation is prepared - then connect the
water pipe (1/2" gas screw connector for size 2 to 5 ; 3/4"
gas screw connector for size 6 and 7).
WARNING: Be sure that the coil protective caps are
removed before connecting the water pipes (see Fig. 19).
NOTE : Each fan-coil units shall be connected with water
flexible pipes in order to avoid any damage due to
vibrations.
Ensure that a gasket (not supplied by Carrier) is installed
between the screw connector and the stop valve.
When all units are installed, open the stop valves on the
manifolds, bleed and then pressurize the circuits. To bleed
the coils, slightly loosen the bleed screws. The installation
can then be started.
NOTE: Do not switch on the power until all connections
are made and earthed.

3.3 - Removal procedure

Switch off the unit power supply at the isolator provided
for the purpose during installation (isolator not supplied
by Carrier).
• Disconnect the power supply and connection cables.
• Close the isolating valves on the manifolds.
• Disconnect the flexible water pipes by unscrewing the
gas connectors.
WARNING: Since the flexible water pipes do not have
drain valves, a receiver must be provided to allow the
cooling coil to be drained.
• Disconnect the supply air ducts.
• Disconnect the flexible condensate drain pipe. Drain
the siphon into a suitable vessel.
• Support the unit lightly and release it by unscrewing
the four nuts on the threaded hangers. Lower the unit
carefully.
20

4 - COMPONENTS AND MAINTENANCE

4.1 - Fan motor assembly

4.1.1 - Fan assembly removal procedure
WARNING: Disconnect the power supply to the unit before
carrying out any work on the unit.
• Identify and note the wired fan speeds. If the fan
develops a fault the whole assembly must be removed
and replaced (Fig. 12).
• Remove the filter.
• Remove the fan access panel.
• Disconnect the fan assembly power supply cables
(power and control wiring for variable-speed motor).
• If necessary remove the controller (fixed with screws)
to gain access to the maintenance screws of the panel
supporting the fan.
• The fan assembly and its panel are held in place by four
screws. Remove these screws and slide the assembly down.
• Remove the fan motor assembly.
NOTE: Be careful not to touch the fan blades during the
removal process to avoid unbalancing the fans.
• For units with the electric heater option, disconnect
the power supply cable to the heater. Withdraw the
cable through the cable gland.
• Unscrew the electric heaters.
• Replacement of the fan motor assembly is by the
reversal of the above procedure.
WARNING: The electrical connections to the fan motor
must be made in accordance with the labels on the
connector block
4.1.2 - Capacitor replacement procedure
• Disconnect the power supply to the unit before
carrying any work on the unit.
• Remove the filter.
• Remove the fan motor assembly access panel.
• Remove the capacitor that is attached to the motor
chassis assembly.
• Disconnect the capacitor by withdrawing the flat
spade connectors from the back of the capacitor.
• Replacement of the capacitor assembly is by the
reversal of the above procedure.
4.1.3 - Fan wiring
For any modifications of the wiring harness, refer to the fan
wiring diagrams provided with the units.
With the optional electrical box, three of the available five
or six speeds of AC motor are connected - (maximum speed
= R1, minimum speed = R5 for 42NH /R6 for 42NL).
When the unit is delivered with an WTC or a NTC controller,
for AC motor, three of the 5 or 6 speeds are connected.
Speeds arrangement can be changed on site according to
the electrical diagram.
WARNING: With the optional electric heater a minimum
air flow must be maintained (see tables below).