1-4
T-312
1.2.2 Compressor Assembly
The compressor assembly (See Figure 1-3.) includes
the refrigerant compressor, clutch assembly, suction
and discharge service valves, high pressure switch,
suction and discharge pressure transducers, suction
and discharge servicing (charging) ports and electric
solenoid unloaders.
The compressor raises the pressure and temperature of
the refrigerant gas and forces it into the condenser
tubes. The clutch assembly provides a means of belt
driving the compressor by the coach engine. The
suction and discharge service valves enable servicing
of the compressor. Suction and discharge access
(charging) ports mounted on the service valves enable
connection of charging hoses for servicing of the
compressor, as well as other parts of the refrigerant
circuit. Transducers convert refrigerant pressures into
electrical signal inputs which are sent to the main
controller. The high pressure switch (HPS) is a normally
closed switch, its contacts open on a pressure rise to
shut down the system when abnormally high refrigerant
pressures occur. The electric unloaders provide a
means of controlling compressor capacity, which
enables control of temperature inside the coach. For
more detailed information on the compressor, refer to
manual number 62-02756.
1.2.3 Evaporator Assemblies
The evaporator assemblies include a driver evaporator
assembly (See Figure 1-4), a main evaporator
assembly (See Figure 1-6), and may include two parcel
rack evaporator assemblies (See Figure 1-5).
The driver evaporator assembly includes an evaporator
coil assembly, a thermal expansion valve, a heater coil
assembly, an evaporator heat valve (EHV), two fan and
motor assemblies, an air filter, and two condensate
drain connections. The evaporator heat valve (EHV) for
the driver evaporator is installed in the piping outside the
evaporator assembly. In addition, the driver evaporator
has an actuator, which controls the outside (RAM) air
damper upon receipt of signal from the main controller.
The main evaporator assembly includes an evaporator
and heater coil assembly, a thermal expansion valve, an
evaporator heat valve (EHV), a fan and motor assembly,
an air filter, and two condensate drain connections.
There is also an evaporator speed fan relay (EFRL),
which changes main evaporator fan speed upon receipt
of a signal from the main controller.
The optional parcel rack evaporator assemblies
includes an evaporator coil assembly, a thermal
expansion valve, a fan and motor assembly,
condensate drain connection, and a return air
thermostat (on the road side only).
The evaporator coils provide a heat transfer surface for
transferring heat from air circulating over the outside
surface of the coil to refrigerant circulating inside the
tubes; thus providing cooling when required. The
thermal expansion valves meter the flow of refrigerant
entering the evaporator coils. The heating coils provide
a heat transfer surface for transferring heat from engine
coolant circulating inside the tubes to air circulating over
the outside surface of the tubes, thus providing heating
when required. The evaporator heat valve(s) (EHV)
controls the flow of engine coolant supplied to the
heating coils. The fans circulate the air over the coils.
The air filters filter dirt particles from the air before the air
passes over the coils.
The condensate drain
connections provide a means for disposing of
condensate collected on the evaporator coils during
cooling operation.
