Exv Troubleshooting Procedure; Exv Valve Replacement; Valve Motor Replacement; Exv Cable Connections To Exv Module - Carrier AquaSnap 30MPA Series Controls, Start-Up, Operation, Service, And Troubleshooting

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EXV Troubleshooting Procedure —
below to diagnose and correct EXV problems.
Check EXV motor operation first. Switch the Enable/Off/
Remote Control (EOR) switch to the Off position. Press
on the scrolling marquee until the display is blank or on Navi-
gator™ display until 'Select a menu item' appears on the dis-
play. Use the arrow keys to select the Service Test mode. Press
. The display will be:
ENTER
> TEST
OFF
OUTS
COMP
Press
(password entry may be required) and use
ENTER
to change OFF to ON. Switch the EOR switch to Enable.
The Service Test mode is now enabled. Move the pointer down
to the OUTS sub-mode and press
item EXV.A. Press
and the valve position will flash. Use
ENTER
to select 100% valve position (hold
ment) and press
.
ENTER
The technician should be able to feel the actuator moving by
placing a hand on the EXV. A sight glass is located on the valve
body to verify that the actuator is moving. A hard knocking
should be felt from the actuator when it reaches the top of its
stroke (can be heard if surroundings are relatively quiet). Press
again twice if necessary to confirm this. To close the
ENTER
valve, press
, select 0% with
ENTER
tuator should knock when it reaches the bottom of its stroke. If
it is believed that the valve is not working properly, continue
with the checkout procedure below.
Check the EXV output signals at appropriate terminals on
the EXV Board (see Fig. 27). Do not disconnect EXV connec-
tor with power applied to the board. Damage to the board may
result if disconnected while under power. Connect positive test
lead to EXV-J6 terminal 3. Set meter to approximately
20 vdc. Using the Service Test procedure above, move the
valve output under test to 100%. DO NOT short meter leads
together or connect pin 3 to any other pin as board damage will
occur.
Fig. 27 — 30MP050-071 EXV Cable Connections
to EXV Module
CAUTION
Do not disconnect EXV connector with power applied to
the board. Damage to the board may result if disconnected
while under power. DO NOT short meter leads together or
connect pin 3 to any other pin as board damage will occur.
During the next several seconds, carefully connect the nega-
tive test lead to pins 1,2,4 and 5 in succession (plug J6). Digital
voltmeters will average this signal and display approximately
Follow steps
ESCAPE
. Move the pointer to
ENTER
for quick move-
and press
. The ac-
ENTER
6 vdc. If it remains constant at a voltage other than 6 vdc or
shows 0 volts, remove the connector to the valve and recheck.
Press
and select 0% to close the valve. Check the 4-
ENTER
position DIP switch on the board (all switches should be set to
On). If a problem still exists, replace the EXV board. If the
reading is correct, the expansion valve and EXV wiring should
be checked.
1. Check color coding and wire connections. Make sure
they are connected to the correct terminals at the EXV
board and EXV plug and that the cables are not crossed.
2. Check for continuity and tight connection at all pin
terminals.
3. If the motor fails to operate properly, check the resistance
of each motor phase. Remove the EXV Board J6 connec-
tor. Check the resistance of the two windings. Resistance
between pins 1 and 2 for one winding or between pins 4
and 5 for the other winding should be approximately 52 ±
5.2 ohms. Differences of more than 10% between wind-
ings indicate a defective motor. Resistance between any
lead and ground should be infinite or "open." Any resis-
tance reading will indicate a shorted winding and the
valve will need to be replaced.
FIELD SERVICING INSTRUCTIONS — See Fig. 26 for a
cutaway view of the EXV. Motor kits for the EXV valve are
available as replacement parts.
EXV VALVE REPLACEMENT — To replace the valve,
perform the following procedure:
1. Be sure the refrigerant has been recovered from the
circuit.
2. Disconnect the EXV cable from the EXV.
3. The valve may be replaced by cutting the piping. A tub-
ing cutter must be used to prevent creating contaminants
in the piping.
4. The EXVs have copper connections and any brazing al-
loy can be used to install the valve. During installation
the torch flame should be directed away from the valve
body and cable. The valve body should be wrapped with
a wet cloth during the brazing operation. Be sure to use a
nitrogen purge while brazing the valve in place.
5. Check for refrigerant leaks.
6. Once the valve body has cooled, reconnect the EXV ca-
ble. Care should be taken to ensure engagement of the
alignment key.
7. Check the operation of the valve using the EXV Trouble-
shooting Procedure on this page.

VALVE MOTOR REPLACEMENT

IMPORTANT: Obtain replacement gasket before opening
EXV. Do not re-use gaskets.
Perform the following procedure to replace the EXV
motor:
1. Be sure the refrigerant has been recovered from the
circuit.
2. Use Service Test to open the EXV to 100%. This will re-
tract the piston fully.
3. Remove power from the EXV board and then disconnect
the EXV Cable from the EXV.
4. Using a wrench and back-up wrench, remove the motor
assembly from the EXV body. Be sure to place the back-
up wrench on the adapter to remove the motor as shown
in Fig. 28.
5. To install the motor, be sure to use a new gasket.
42

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