Thermo King SB-190 30, Руководство пользователя

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Refrigeration Maintenance (Rev. 12/03)
62
ELECTRONIC THROTTLING VALVE
(OPTIONAL)
The optional Electronic Throttling Valve (ETV) is a vari-
able position valve operated by a stepper motor. The ETV is
located in the suction line between the evaporator and the
heat exchanger. The ETV system also uses discharge and
suction pressure transducers, and a hot gas bypass valve.
The ETV has two internal coils. The microprocessor oper-
ates the valve by energizing the coils with a variable fre-
quency ac signal. The valve position can be monitored with
the GAUGE key [ETV.P]. Zero (0) indicates the valve is
fully closed and 800 indicates the valve is fully open.
The microprocessor tests the ETV every time the unit is
started. Alarm Code 89 indicates the refrigeration system
pressures did not respond as expected during the test. This
may be caused by a malfunction of the ETV or by a refriger-
ation system problem such as low refrigerant level, a frozen
expansion valve, or a restriction in suction line. The micro-
processor ignores the test results if the box temperature or
the ambient temperature is below 10 F (-12 C). The ETV
test can also be performed using the Service Test Mode
(Service Procedure A34A in TK 50566).
Use the GAUGE key to check the operation of the ETV dur-
ing the ETV test. The valve position [ETV.P] should be 0 at
the start of the test when the valve is fully closed, and
should go to a higher value when the valve is opened. The
suction pressure [SUC.P] should decrease while the valve is
fully closed, and should begin to increase when the valve is
opened.
Refer to Service Procedure G03A, the Electronic Throttling
Valve (ETV) Test, and Alarm Code 89 in the THERMO-
GUARD
µ
P-VI Microprocessor Controller Diagnosis Man-
ual TK 50566 for complete information about the testing
and operation of the ETV.
PRESSURE TRANSDUCERS (OPTIONAL)
The discharge pressure transducer and the suction pressure
transducer supply pressure information to the microproces-
sor. These pressures can be monitored with the GAUGE
key. [DIS.P] is the discharge pressure. [SUC.P] is the suc-
tion pressure. The readings can be checked by comparing
them to the readings on a gauge manifold set attached to the
compressor. Refer to Service Procedure D03A, the Pressure
Sensor Test, and Alarm Codes 87 and 109 in the THERMO-
GUARD
µ
P-VI Microprocessor Controller Diagnosis Man-
ual TK 50566 for more information about the testing and
operation of the pressure transducers.
ARA168
2
3
1. Outlet
2. Stepper Motor
3. Valve Body
4. Inlet
Electronic Throttling Valve
1
4