Manual Operation
Selecting MAN enables the spring-loaded
ON–OFF switch to control the shutoff valve
and, therefore, the amount of bleed air supplied
to the windshields.
On the ground, in manual mode, a low-limit
thermoswitch illuminates the WSHLD OV’HT
light, but does not close either the regulator
valve or shutoff valve.
If the temperature activates the high-limit
switch, the pressure-regulator valve closes.
In flight, the low-limit switches are disabled.
Overheat protection is provided by the high-
limit switches which close the pressure-
regulator valve, if activated.
WINDSHIELD/RADOME
ALCOHOL ANTI-ICE SYSTEM
General
Methyl alcohol, from a reservoir (Figure 10-
10) located in the left side of the nose com-
partment, is provided to prevent ice formation
10-8
FOR TRAINING PURPOSES ONLY
LEARJET 20 SERIES PILOT TRAINING MANUAL
FlightSafety
international
CONDITIONED AIR
BLEED-AIR DUCT
MANUAL DEFOG CONTROL VALVE
EXTERNAL DEFOG OUTLET
HIGH-LIMIT THERMOSWITCH
LOW-LIMIT THERMOSWITCH
EXTERNAL DRAIN
FOOTWARMER
INTERNAL DEFOG NOZZLE
DEFOG CONTROL
KNOB
FWD
Figure 10-9.
Windshield Heat Diagram