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7-4. SC Circuit Electronic Control Valve [MOV4]
(1) SC Control (Cooling Mode only
During cooling operation, the liquid refrigerant which condenses at the outdoor unit heat exchanger flows into
the receiver tank, and SC (sub-cool = supercooling) approaches 0°F. When SC is small and the length of the
tubing connecting the indoor and outdoor units is long, the refrigerant flow in the indoor unit will be reduced sig-
nificantly. To prevent this trouble from occurring, MOV4 operates so as to increase supercooling in the double
tube coil near the outlet of the outdoor unit.
MOV4 controls refrigerant so that it will not flow back to the compressor in the liquid state with a suction tem-
perature sensor near the accumulator and a low pressure sensor.
(2) Operation when discharge temperature is high
When the discharge temperature increases, the SC circuit electronic thermostatic expansion valve opens to
480 pulses to cool down the compressor. This operation takes priority over operation intended to increase SC.
It is performed at top priority in all operating modes. In addition, the valve opening adjustment will be made
when the discharge temperature falls.
Gas refrigerant returns
to the accumulator.
Liquid refrigerant
(large SC)
Liquid refrigerant (SC = 0°F)
Refrigerant on the outer side evaporates,
cooling the liquid refrigerant on the inner side.
Electronic control valve 4
(expansion valve) controls the flow.
Does not fully evaporate,
resulting in liquid back-up.
Liquid refrigerant returns
to the accumulator.
Liquid refrigerant
Electronic control valve
4 opens to 480 pulses.
Liquid refrigerant
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7. Outdoor Unit Electronic Thermostatic Expansion Valves
[MOV1, MOV2 & MOV4]
W-2WAY ECO-i SYSTEM
Control Functions