control valve and opens to prevent muscle pressure to
the warm air temperature control valve when duct
temperature exceeds sensor settings.
Flow/Temperature Limiting Anti-Ice
Modulating Valve
The flow/temperature limiting anti-ice modulating
valve (fig. 5-7, item B), located downstream of the
warm air temperature control valve, is a dual function
valve. It is a pneumatically actuated flapper valve and a
muscle pressure that is controlled by the warm air
over-temperature sensor. The valve is normally open
during system operation and modulates toward closed
only if an over-temperature condition occurs. The
muscle pressure regulator on this valve is the source of
regulated muscle pressure used by the environmental
control systems. It is a dual diaphragm regulator and
uses source air pressure from either the windshield
anti-ice and rain removal duct or the air cycle
air-conditioning system, depending on which pressure
is greater.
Warm Air Over-Temperature Sensor
Figure 5-8.--Anti-ice/rain removal air control regulating
The warm air over-temperature sensor (fig. 5-7,
valve.
item C) is located downstream of the flow/temperature
limiting anti-ice modulating valve. It opens if duct
causing the digital display indicator to display a
temperature reaches 375F 25F to vent muscle
WDSHLD HOT caution message.
pressure from the flow/temperature limiting anti-ice
modulating valve. This causes the valve to modulate
Windshield Anti-Ice/Rain Removal Switch
toward closed and restricts airflow to protect the
windshield from overheat damage.
This is a three-position control switch. The switch
in OFF position removes power from the anti-ice/rain
Anti-Ice/Rain Removal Air Control
removal air control regulating valve to close the valve
Regulating Valve
and shutoff airflow to the windshield. The switch in
RAIN position allows low pressure (5.4 pounds per
The anti-ice/rain removal air control-regulating
square inch gauge [psig]) and low volume (20 pounds
valve (fig. 5-8) completes the final pressure regulation
per minute [lbs/min]) air at 250F directed across the
and flow control before airflow reaches the anti-ice/rain
windshield through the anti-ice/rain removal nozzle.
removal nozzle. The valve regulates pressure and flow
The switch in ANTI-ICE position allows high pressure
rate relative to position of the WINDSHIELD
(29.5 psig) and high volume (57 lbs/min) air at 250F
ANTI-ICE/RAIN removal switch.
directed across the windshield through the anti-ice/rain
removal nozzle.
Windshield Overheat Temperature Sensor
OPERATION
The windshield overheat temperature sensor,
located downstream of the anti-ice/rain removal air
The windshield anti-ice and rain removal system is
control regulating valve, is a temperature-activated
used to supply controlled airflow to the anti-ice/rain
switch, which opens if airflow temperature reaches
removal nozzle to remove ice and/or rain from
290 5F. It closes when airflow temperature drops to
the windshield. The WINDSHIELD ANTI-ICE/RAIN
280 5F. When the switch is open, a ground is lost to
removal switch controls the modes of operation.
the signal data converter and the signal data computer,
5-10
