(1) Direct heated air to cab ducts by use of baffle
off heater before damaging temperature is
levers on plenum chamber as directed by
instruction plate. Begin defrost function after
cab has become noticably warmer.
(2) A blower is provided to produce an increase in
Do not turn off oil pressure switch
volume of air sent through system.
manually. If this precaution is not
automatic control will operate blower in
observed, switch will not continue to
accordance with preset temperatures.
blower switch is located on light switch box.
Movement of baffle lever behind blower (fig.
b. Cab heating and defrosting functions are
93) will select warmed inside air,
accomplished by manipulation of baffle levers on large
fresh out side air to the system. Choose
position indicated on instruction plate.
153. Engine Coolant Heater
Before starting defrost operation at
low ambient temperature, open lower
a. The engine coolant heater is located in a
baffle of plenum chamber (control for
housing on left side of crane upper section (fig. 94).
foot warmer) and heat cab for
This heater maintains proper operating temperature of
approximately 15 minutes.
engine coolant and lubricating oil in engine oil pan. A
precaution must be observed to
pump circulates a continuous flow of heated coolant
prevent glass breakage, which could
throughout system, including a tubular coil inserted in
occur when directing hot air at
engine oil pan.
extremely cold glass.
Figure 94. Engine coolant heater.