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Check the resistance of the two windings between pins 1 and 3
for one winding and pins 2 and 4 for the other winding. The re-
sistance should be 52 ohms (± 5.2 ohms).
Inspecting/Opening Electronic Expansion Valves
IMPORTANT: Obtain replacement gaskets before
opening EXV. Do not re-use gaskets.
To check the physical operation of an EXV, the following
steps must be performed.
1. Close the liquid line shut off valve of the circuit to be
checked. Put the Enable/Off/Remote Contact switch in
the Off position. Using the scrolling marquee, enter the
Service Test mode and change Service Test
T.REQ from OFF to ON. A password may be
required. Switch the EOR switch to the Enable position.
Under the COMP sub-mode, enable the one of the com-
pressors (Service Test
Let compressor run until gage on suction pressure port
reads 10 psig. Press
ENTER
the compressor off. The compressor will turn off. Imme-
diately after the compressor shuts off, close the discharge
valve.
2. Remove any remaining refrigerant from the system low
side using proper reclaiming techniques. Turn off the line
voltage power supply to the compressors.
3. The expansion valve motor is hermetically sealed inside
the top portion of the valve. See Fig. 24. Carefully
unscrew the 1
1
/
in. (27 mm) retaining nut securing the
16
motor portion to the body of the valve making sure the
EXV plug is still connected. The EXV operator will come
out with the motor portion of the device.
4. Enter the appropriate EXV test step under the (Service
Test
QUIC) sub-mode in the Service Test mode.
Locate the desired item Service Test
Service Test
QUIC
EXV.C. Press
ENTER
tion of 0% flash. Press and hold
played and press
ENTER
lead screw. See Fig. 25. The motor should be turning,
raising the operator closer to the motor. Motor actuator
movement should be smooth and uniform from fully
closed to fully open position. Press
to select 0% and press
to closed operation. If the valve is properly connected to
the processor and receiving correct signals, yet does not
operate as described above, the sealed motor portion of
the valve should be replaced.
Installing EXV Motor
IMPORTANT: Obtain replacement gasket before
opening EXV. Do not re-use gaskets.
If re-installing the motor, be sure to use a new gasket in the
assembly. See Fig. 26. It is easier to install the motor assembly
with the lead screw in the fully closed position. Using the steps
outlined above, move the EXV position to 0. Insert the motor
into the body of the EXV. Tighten the motor to the body to
36 ft-lb (50 N-m) and then tighten the valve another 30 degrees.
Moisture Liquid Indicator — Clear flow of liquid refrigerant
indicates sufficient charge in system. Bubbles in the sight glass
indicate undercharged system or presence of noncondensables.
TEST
TEST
CP.xn) for the circuit.
,
and
to turn
ENTER
QUIC
EXV.A,
EXV.B, or Service Test
QUIC
twice to make the valve posi-
until 100% is dis-
. Observe the operation of the
twice, use
ENTER
again to check open
ENTER
Moisture in system measured in parts per million (ppm),
changes color of indicator. See Table 36. Change filter drier at
first sign of moisture in system.
Table 36 — Moisture Liquid Indicator
REFRIGERANT R-410A
Green — Dry
Yellow-green — Caution
Yellow — Wet
IMPORTANT: Unit must be in operation at least
12 hours before moisture indicator can give an accu-
rate reading.
With unit running, indicating element must be in con-
tact with liquid refrigerant to give true reading.
Filter Drier — Whenever moisture-liquid indicator shows
presence of moisture, replace filter drier(s). There is one filter
drier on each circuit. Refer to Carrier Standard Service
Techniques Manual, Chapter 1, Refrigerants, for details on
servicing filter driers.
Liquid Line Service Valve — This valve is located immediately
ahead of filter drier, and has a
field charging. In combination with compressor discharge
service valve, each circuit can be pumped down into the high
side for servicing except on units equipped with MCHX con-
denser coils.
Cooler
FREEZE PROTECTION — Coolers can be ordered with
heaters installed in the factory. If equipped, the main base
board based on the outdoor-air temperature and the entering
and leaving water thermistors controls the cooler heaters. The
Heater Set Point is the sum of the freeze point and Cooler
Heater DT Setp (Configuration
If the entering or leaving water temperature is less than the
Heater Set Point and the outdoor air temperature is less than
the Heater Set Point – 2° F (1.1° C), then the heater will be
turned on.
If the Entering or Leaving Water Temperature is less than
the Brine Freeze Setpoint (Configuration
1.0° F (0.5° C), then the heater will be turned on along with the
pump.
Entire cooler is covered with closed-cell insulation applied
over the heater. Heater plus insulation protect cooler against
low ambient temperature freeze-up to –20 F (–28 C).
IMPORTANT: If unit is installed in an area where
ambient temperatures fall below 32 F (0° C), it is rec-
ommended that a suitable corrosion-inhibited anti-
freeze solution be used in chilled water circuit.
LOW FLUID TEMPERATURE — Main base board is pro-
grammed to shut chiller down if leaving fluid temperature
drops below 34 F (1.1 C) for water or below Brine Freeze
Setpoint (Configuration
unit will shut down without a pumpout. When fluid tempera-
ture rises to 6° F (3.3° C) above the leaving fluid set point,
safety resets and chiller restarts. Reset is automatic as long as
this is the first occurrence.
LOSS OF FLUID FLOW PROTECTION — All 30RB ma-
chines include an integral flow switch that protects the chiller
against loss of cooler flow.
TUBE PLUGGING — A leaky tube can be plugged until
retubing can be done. The number of tubes plugged determines
how soon the cooler must be retubed. If several tubes require
51
AT 75 F (24 C)
AT 125 F (52 C)
(ppm)
(ppm)
<20
<60
20 to 165
60 to 500
>165
>500
/
-in. Schrader connection for
1
4
SERV
HTR).
SERV
SERV
LOSP) for brine units. The
LOSP) +
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