Zanotti Zer0 120, Руководство по ремонту

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9
1.2 EVAPORATOR SECTION
The evaporator is mounted on the ceiling inside the
vehicle box. The evaporator assembly consists of an
evaporator fan, evaporator coil, and thermostatic
expansion valve, hot gas solenoid, temperature
probe.
1.2.1 Thermostatic expansion valve
The thermostatic expansion valve (TXV valve) is an
automatic device that controls the flow of liquid to
the evaporator according to changes in superheat of
the refrigerant leaving the evaporator. The thermal
expansion valve maintains a relatively constant
degree of superheat in the gas leaving the evaporator
regardless of suction pressure. Thus, the valve has a
dual function; automatic expansion control and
preventing liquid from returning to the compressor.
For TXV superheat settings see Section 4.14.1
1.2.2 Evaporator coil
The evaporator is of the tube and fin type. The
operation of the compressor maintains a reduced
pressure within the coil. At this reduced
pressure, the liquid refrigerant evaporates at a
temperature sufficiently low enough to absorb heat from
the air. Air movement over the evaporator is provided by
an electric fan.
1.2.3 Defrost coil
Coil lined under evaporator pan to defrost ice.
1.2.4 Evaporator drain tube heaters
Evaporator heaters are used to avoid drain tube blockage
because of ice accumulation inside the evaporator. Two
harnesses are located inside the drain tube. These resistive
wires melt the ice while the unit is in DEFROST mode.
1.2.4 Hot gas solenoid valve
The hot gas solenoid valve is normally closed and prevents
discharge gas from entering the evaporator. The valve
opens to allow hot gas refrigerant to be delivered from the
compressor to the evaporator during heat or defrost
modes.
Figure 2 - Z120 Evaporator Section Components