CSP−900RMM−2MD Helicopters, Inc.
Rotorcraft Maintenance Manual
Page 3
Revision 8
21-50-00
K. Thermostatic Switch
The thermostatic switch is in the evaporator
cooling duct.
The thermostatic switch controls the compres
sor. The thermostatic switch prevents an icing
condition or too much refrigeration.
L. Thermostatic Expansion Valve
The thermostatic expansion valve (TXV) is in
the evaporator.
The valve controls the high pressure liquid
refrigerant flow that goes into the evaporator
as a gas.
The valve is a spray nozzle. It is in operation
at the same time as the compressor. The valve
adjusts for temperature to control the liquid
refrigerant flow into the evaporator.
M. Evaporator Assembly
The evaporator assembly is in a housing that
attaches to the air plenum duct.
The evaporator supplies a heat exchange for
the cabin air to cool. The internal chamber of
the evaporator lets the low pressure liquid
refrigerant expand into a low temperature gas.
When the AC/VENT rotary switch is set to
COOL HIGH or COOL LOW the evaporator
fan energizes. The fan then recirculates the
cabin air or fresh air through the evaporator.
The three-way valve opens to let warm cabin
air or fresh air go into the fresh air vent
system ducts. The low pressure gas in the
evaporator cools the air that flows over the
evaporator.
N. Evaporator Fan
The evaporator fan is on the right side of the
evaporator.
A two speed 28 Vdc electric motor energizes
the evaporator fan. The fan starts the airflow
that moves the cabin air or fresh air through
the evaporator. The air cools as it flows over
the evaporator. The routing of the ducts sends
the air to the cabin gasper assemblies.
O. Three−Way Valve Duct Assembly
The three-way valve duct assembly is next to
the water separator.
The duct assembly lets the air move through
the air conditioning ducts to cool the crew and
passenger compartment.
P. Three Way Valve
The three way valve is next to the evaporator
fan.
The three way valve is a butterfly disc valve.
The three way valve lets cabin recirculated air,
outside fresh air, or both into the air condition
ing system.
Q. Three−Way Valve Control Cable
The three-way valve control cable is above the
right pilot seat.
The three-way valve control cable is a push
pull cable. The three-way valve control cable
operates the three way valve. The pilot can set
the cable position for outside fresh air, cabin
recirculated air, or both.
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