Specifications

67
Table 40 — EXV Modes and Submodes
INSPECTING/OPENING ELECTRONIC EXPANSION
VA LV E S
To check the physical operation of an EXV, the following
steps must be performed.
1. Close the liquid line service valve of the circuit to be
checked. Put the Enable/Off/Remote Contact (EOR)
switch in the Off position. Enter the Service Test mode
and change Service Test Enable, 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 one of the compressors (CP.xn) for the cir-
cuit. Let compressor run until gage on suction pressure
port reads 10 psig (68.9 kPa). Turn the compressor off.
The compressor will turn off. Immediately after the com-
pressor shuts off, manually close the actuated ball valve
(ABV). If the unit is equipped with suction service valves
and economizer service valves, close both valves. Clos-
ing the valves will minimize the amount of charge that
will have to be removed from the system after pump
down.
2. Remove any remaining refrigerant from the system low
side using proper recovering techniques. The economizer
assembly has a
1
/
4
-in. access connection which can be
used to remove charge from the inlet of the EXVs. 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. 49. Disconnect the
EXV plug. Carefully unscrew the motor portion from the
body of the valve. The EXV operator will come out with
the motor portion of the device. Reconnect the EXV plug.
4. Enter the appropriate EXV test step under the (QUIC)
Service Test mode Locate the desired item Circuit A
EXV Position, EXV.A or Circuit B EXV Position,
EXV.B. Change the position to 100%. Observe the opera-
tion of the lead screw. See Fig. 49. 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. Select 0% and check
open to closed operation. If the valve is properly connect-
ed 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
If re-installing the motor, be sure to use a new gasket in the
assembly. See Fig. 50. It is easier to install the motor assembly
with the piston in the fully closed position. 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.
Moisture in system, measured in parts per million (ppm),
changes color of indicator. See Table 41. Change filter drier at
first sign of moisture in system.
Table 41 — Color Indicators when
Moisture is Present in Refrigerant
Filter Drier — Whenever moisture-liquid indicator shows
presence of moisture, replace filter drier(s). There is one filter
drier assembly on each circuit with two cores. Refer to the Car-
rier Standard Service Techniques Manual, Chapter 1, Refriger-
ants, for details on servicing filter driers.
Liquid Line Service Valve — This valve is located immediately
ahead of filter drier, and has a
1
/
4
-in. access connection for field
charging. In combination with compressor discharge service
valve, each circuit can be pumped down into the high side for
servicing.
Compressor Assembly — The 30XW units utilize
screw compressors with a modulating slide valve which varies
capacity from 15% to 100% of compressor capacity for each
circuit. See Fig. 51 for a view of a typical 06T compressor.
The slide valve position is varied by opening and closing the
2 solenoid valves located on the compressor. To unload the
compressor, both solenoids are deenergized. To increase in
capacity both solenoid valves are energized together which
will cause the slide valve to slide towards the fully loaded posi-
tion. To stop the loading process solenoid 2 is energized and
solenoid 1 is deenergized. This will cause the slide valve to
maintain its current position. There is no feedback for the posi-
tion of the slide valve. The control utilizes compressor current
as an indicator of the slide valve position. Once the calculated
position of the slide valve reaches 100% circuit capacity, the
control will try to increase capacity again if the compressor
current continues to increase. The control will continue to load
the compressor until the compressor current no longer
increases. At that time the control will energize both solenoids
and the circuit will be considered fully loaded.
EXV TYPE AND CIRCUIT TOUCH PILOT™ PATH NAVIGATOR™ PATH
EXV, Circuit A Main Menu Status QCK_TST1 Q_EXVA Service Test Mode QUIC EXV.A
EXV, Circuit B Main Menu Status QCK_TST1 Q_EXVB Service Test Mode QUIC EXV.B
Economizer EXV, Circuit A Main Menu Status QCK_TST1 Q_ECO_A Service Test Mode QUIC ECO.A
Economizer EXV, Circuit B Main Menu Status QCK_TST1 Q_ECO_B Service Test Mode QUIC ECO.B
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IMPORTANT: Obtain replacement gaskets before
opening EXV. Do not re-use gaskets.
CAUTION
Ensure refrigerant is removed from both the inlet and outlet
of EXV assemblies. Equipment damage could result.
IMPORTANT: Obtain replacement gasket before
opening EXV. Do not re-use gaskets.
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.
COLOR INDICATOR
R-134a,
75 F (24 C)
(ppm)
R-134a,
125 F (52 C)
(ppm)
Green — Dry <30 <45
Yellow-green — Caution 30-100 45-170
Yellow — Wet >100 >170