Carrier NDK33BN0KB, Руководство по эксплуатации и обслуживанию

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62-61753-21 8-21
2-1/8 inch Nut
CSMV
4 PIN CONNECTOR
Figure 8-14. Suction modulation valve (CSMV)
If it is suspected that the SMV is malfunctioning, the
most efficient method of diagnosing the valve is to run
a pretrip (refer to Section 3.4). The pretrip steps will
check the remainder of the system and the #10 test
will check the SMV. The valve will be brought to a
preset position, the unit started and then the valve will
be opened while the microprocessor monitors suction
pressure. If there is a problem with the valve, valve
stepper motor or microprocessor wiring to the valve
the test will fail.
Diagnostics - Microprocessor or Wiring
a. Locate the wires, on the engine harness side of the
SMV connector labeled CSMVA, CSMVB, CSMVC
and CSMVD. These will correlate to the connector
pins labeled A, B, C and D. Refer to Table 8-2.
Table 8-2. CSMV Connections
Connector Pin Wire Color Winding/Pole
A BLACK 1A
B WHITE 1B
C RED 2B
D GREEN 2A
b. Place the SROS in the Start/Run position. DO NOT
ALLOW THE UNIT TO START. When the Mes-
sageCenter displays "SMV CLOSING", measure the
AC voltage between pins A and B and then between
C and D. A reading of 10 to 16 VAC should be read
by the digital voltmeter for each pair of wires. If the
reading of 10 to 16 VAC is present on both of the
wire pairs there is a good signal coming from the
microprocessor.
c. If the reading of 10 to 16 VAC is not present on one
or both of the wire pairs, check the wiring between
the microprocessor and the SMV connector, or
check the microprocessor for proper model number
Configuration.
Diagnostics - Stepper Motor
The valve stepper motor may be tested using a step-
per motor drive tester or ohmmeter.
a. To test with a stepper motor drive tester (Carrier
Transicold part number 07-00375-00), connect the
4 pin test cable to the valve connector, refer to Ta-
ble 8-2, and the cable wires to the tester in accord-
ance with wire and terminal color.
b. Set the step rate to 200 steps per second and either
open or close the valve. Each red LED should light
sequentially until all four are illuminated. Any LED
failing to illuminate indicates an open on that leg and
a need to replace the piston and drive motor as-
sembly.
c. To test with an ohmmeter, check the winding re-
sistance between connector pin 1A & 1B and then
between 2A & 2B, see Figure 8-14. In normal ambi-
ent, the resistance between the pins should be 72 to
84 ohms. If an infinite or zero reading is observed,
the piston and drive motor assembly is to be re-
placed.
1
2
B 1 ) E T I H W ( ) K C A L B ( A 1
(RED) 2B
2A (GREEN)
Figure 8-15. CSMV Coil (Bi-Polar Design)
Diagnostics - Valve
NOTE
If the valve failed pretest and passed the pre-
ceding diagnostic testing, this is an indication
that the valve internal mechanism is damaged
and the piston and motor assembly is to be
replaced.
a. To test the valve internal mechanism, connect a
gage to the suction service valve and a stepper mo-
tor drive tester.
CAUTION
The scroll compressor achieves low suc-
tion pressure very quickly. Do not use the
compressor to evacuate the system below
0 psig. Never operate the compressor with
the suction or discharge service valves
closed (frontseated). Internal damage will
result from operating the compressor in a
deep vacuum.
b. Start the unit, set the step rate to 200 steps per
second and close the valve while watching the suc-
tion pressure. Within one minute the suction pres-
sure should begin to fall. Place the SROS in the
OFF position before the reading enters a vacuum.
c. If the suction pressure does not change, this is an
indication the valve is stuck and the piston and drive
motor assembly is to be replaced.
Replacing the Drive and Motor Assembly
a. Remove the refrigerant charge. (Refer to section
8.5.1).
b. Remove valve piston and motor assembly and re-
place with a new assembly and gasket. The power
head should be set to 100% open when received
from the warehouse. This is to ensure the Teflon
valve seal is not damaged when it is installed. En-
sure the valve is fully open by using the stepper mo-