Heater Coil; Fan Motor And Speed Control; Actuators; Air Conditioner Components - Komatsu 930E-2 Shop Manual

HEATER COIL

The heater coil (12, Figure 3-5) receives coolant
through the water control valve (44) when HEAT is
selected. If the selection control (19) is placed in
between the red and blue area, or turned counterclock-
wise to the blue area, coolant flow should be blocked.
If the heater control module (43) and water valve
appear to be working properly, yet no heat is apparent
in the heater coil (12), the coil may be restricted.
Remove and clean or replace the coil.

FAN MOTOR AND SPEED CONTROL

Fan speed is controlled by inserting resistor(s) (29 &
30) 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 supplied to the blower motor, bypassing all resistors.
Test
If the motor (39) does not operate at any of the speed
selections, verify battery voltage is available at the
circuit breakers (refer to electrical schematic, Section
R). If voltage is present, the motor is probably defec-
tive 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 3-5) 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 caused by a faulty actuator.
N3-4
Test
Visually inspect the flapper (8, 26, or 31) and linkage
for the function being diagnosed. Make certain the
flapper is not binding or obstructed, preventing move-
ment 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.

FILTER

Service
Inlet filters (6) 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, unique to
the air conditioner system, are discussed in Section M,
"Air Conditioning System" .
Cab Components N03011 7/98