Owner's Manual

REFRIGERATION SYSTEM
MTC-15
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MTC
REFRIGERATION SYSTEM PFP:KA990
Refrigeration Cycle EJS001AI
REFRIGERANT FLOW
The refrigerant flows in the standard pattern, that is, through the compressor, the condenser, the liquid tank,
through the evaporator, and back to the compressor. The refrigerant evaporation through the evaporator coil is
controlled by an externally equalized expansion valve, located inside the evaporator case.
FREEZE PROTECTION
The compressor cycles go on and off to maintain the evaporator temperature within a specified range. When
the evaporator coil temperature falls below a specified point, the intake sensor interrupts the compressor oper-
ation. When the evaporator coil temperature rises above the specification, the thermo control amplifier allows
compressor operation.
REFRIGERANT SYSTEM PROTECTION
Refrigerant Pressure Sensor
The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sen-
sor, located on the refrigerant lines where they attach to the condenser. If the system pressure rises above or
falls below the specifications, the refrigerant pressure sensor detects the pressure inside the refrigerant line
and sends the voltage signal to the ECM. The ECM turns the A/C relay OFF and stops the compressor when
pressure on the high pressure side detected by refrigerant pressure sensor is over about 2,746 kPa (28 kg/
cm
2
, 398 psi) or below about 177 kPa (1.8 kg/cm
2
, 26 psi).
Pressure Relief Valve
The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compressor.
When the pressure of refrigerant in the system increases to an abnormal level [more than 3,727 kPa (38 kg/
cm
2
, 540 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into
the atmosphere.
WJIA0419E