Carrier Transicold X4 7300, Operation & Service Manual

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62-11637 8–40
c. Diagnostics Valve
NOTE
If the valve failed pretest and passed the
preceding diagnostic testing, this is an indi-
cation that the valve mechanism is damaged
and the internal motor/piston assembly is to
be replaced.
1. To test the valve internal mechanism, install a
manifold gauge set on the suction service valve
and a stepper motor drive tester.
2. Start the unit, set the step rate to 200 steps per
second and close the valve while watching the
suction pressure. Within one minute the suction
pressure should begin to fall. Place the STOP/
RUN-OFF switch in the OFF position before the
reading enters a vacuum.
3. If the suction pressure does not change, this is
an indication the valve is stuck and the internal
motor/piston assembly is to be replaced.
d. Replacing The Internal Motor/Piston Assembly
1. Pump down the low side. Refer to Section
8.7.2 .
2. Remove internal motor/piston assembly and
replace with a new assembly and gasket. The
motor/piston assembly should be set to 100%
open when received from the warehouse. This
is to ensure the Teflon valve seal is not dam-
aged when it is installed. Ensure the valve is
fully open by using the stepper motor tester to
manually open the valve to 100% before it is
installed. Torque the body screws 80 to 97 inch/
lbs (9 to 11 Nm).
3. Leak check, evacuate & dehydrate, and charge
system as required. Refer to Section 8.7.2 ,
8.7.3 & 8.7.4 .
e. Emergency Repair Procedures
In the event that the CSMV system has a failure, and
replacement components are not readily available in
an emergency, a
LIMP-HOME procedure can be done
as follows:
1. Install a manifold gauge set.
2. Pump down the low side. Refer to Section
8.7.2 .
3. Remove the internal motor/piston assembly.
4. Loosening the Allen screw and remove the pis-
ton and screw.
5. Install the motor/piston assembly (without pis-
ton). Torque the nut 35 to 40 ft/lb (47.5 to 54.2
Nm) or body screws 80 to 97 inch/lbs (9 to 11
Nm) as applicable.
6. Leak check, evacuate & dehydrate, and charge
system as required. Refer to Section 8.7.2 ,
8.7.3 & 8.7.4 .
7. Start the unit.
8. Adjust the suction service valve so that the
approximate temperature is maintained. For
perishable loads, it is recommended that the
adjustment be made so that the available
capacity is slightly larger than the load, the unit
will cycle OFF and ON.
9. Once repair parts become available, repair as
required.
8.9.9 Evaporator Expansion Valve
The evaporator expansion valve (EVXV − see Figure
8.36 ) is a microprocessor driven device which meters
the flow of refrigerant into the coil. The flow control pro-
vides: (a) response to match the evaporator load and
(b) prevention of liquid refrigerant return to the com-
pressor. Unless the valve is defective, it seldom
requires any maintenance.
NOTE
As a preliminary check, ensure the EVXV
coil is snapped down fully, and the internal
coil retention tab is properly seated in one of
the valve body dimples.
Figure 8.36 Evaporator Expansion Valve
a. Diagnostics - Microprocessor or Wiring
1. Disconnect the 2SVM connector and locate the
wires, on the engine harness side labeled
EXVA, EXVB, EXVC, EXVD and EXVE. These
will correlate to the connector pins labeled A, B,
C, D and E. Refer to
Table 8–2 .
FLOW
DIRECTION
Evaporator Expansion Valve
Coil
Body Dimples
Five Pin
Connector