Komatsu 830E-AC Shop Manual page 931

Fan Motor And Speed Control
Fan speed is controlled by inserting resistor(s) (52 &
53, Figure 4-4) in series with the supply circuit to the
blower motor to reduce voltage. The number of resis-
tors 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; at high speed, the full 24 VDC is
supplied to the blower motor, bypassing all resistors.
Test
If motor (5) does not operate at any of the speed
selections, verify battery voltage is available at the
switches, relay, and circuit breakers (refer to electri-
cal schematic, Section R). If voltage is present, 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 resis-
tors as required.
Actuators
Two rotary actuator motors (8, 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
A failure to switch one of the above modes of opera-
tion may be caused by a faulty actuator.
Test
Visually inspect the flappers (11, 44') and linkage for
the function being diagnosed. Make certain the flap-
per is not binding or obstructed, preventing move-
ment from one mode to the other.
Verify voltage (12 VDC) is present at the actuator
when the toggle switch is closed or absent when the
toggle switch is opened.
If the correct voltages are present during operation of
the switch, disconnect the actuator from the flapper
and verify actuator force is comparable to a known
(new) actuator. If not, replace with a new actuator.
N04031 10/06
Cab Air Filter
Recirculation air filter (19, Figure 4-4) and fresh air
filter (2, Figure 4-3) in the front access panel of the
cab need periodic cleaning to prevent restrictions in
air circulation. Restricted filters will decrease the per-
formance of the heater and air conditioner. The rec-
ommended interval for cleaning and inspection is
250 hours, but in extremely dusty conditions, the fil-
ters may need daily service and inspection, espe-
cially the outer panel filter on the cab shell. The filter
elements should be cleaned with water and dried in a
dust free environment before reinstallation. Replace
the filter element every 2000 hours or sooner if
inspection indicates a clogged or damaged filter.
FIGURE 4-3. CAB FILTER LOCATION
1. Access Cover
Operator Comfort
2. Cab Filter
N4-5