Komatsu 930E-2 Shop Manual page 658

FAN MOTOR AND SPEED CONTROL
Fan speed is controlled by inserting resistor(s) in series
with the supply circuit to the blower motor to reduce
voltage. The number of resistors in series is determined
by the position of the fan speed selector switch.
At low speed, 3 resistors are used, at medium speed,
1 resistor is used, and for high speed, the full + 24VDC
is suppplied to the blower motor, bypassing all resis-
tors.
Test
If the motor does not operate at any of the speed
selections, check voltage supplied to the motor. If
approximately 24 volts (at high speed setting) is avail-
able, the motor is probably defective and should be
removed and replaced.
If the motor operates at high speed, but does not
operate at reduced speed, inspect the resistors for
physical damage or an open circuit. Replace resistors
as required.
ACTUATORS
Three (3) linear actuators (22, Figure 4-4) are installed
inside the heater housing and are used to actuate the
flappers for the following:
• Defroster outlet
• Bi-level or floor outlets
• Inside or outside air selection
A failure to switch one of the above modes of operation
may be due to a faulty actuator.
Test
Visually inspect the flapper and linkage for the function
being diagnosed. Make certain the flapper is not bind-
ing or obstructed, preventing movement from one
mode to the other.
Verify voltage is present at the actuator when the toggle
switch is closed or absent when the toggle switch is
opened.
If voltage is proper, disconnect actuator from flapper
and verify actuator force is comparable to a known
(new) actuator. If not, replace with a new actuator.
N4-4
FILTER
Service
Inlet filters in the heater cover and the cab access panel
need periodic cleaning to prevent restrictions in air
circulation. The recommended interval for cleaning
and inspection is 250 hours, but in extremely dusty
conditions, the filters may need daily service and in-
spection, especially the outer panel filter on the cab
shell. The filter elements should be cleaned with water
and dried in a dust free environment before reinstalla-
tion. Replace the filter element every 2000 hours or
sooner if inspection indicates a clogged or damaged
filter.
AIR CONDITIONER COMPONENTS
Components installed in the heater housing are dis-
cussed in Section M, "Air Conditioning System" .
Operator Comfort N04020