Komatsu PC200-8M0 Shop Manual page 1168

SEN06151-00
A: Refrigerant inlet (from condenser)
B: Refrigerant outlet (to compressor)
C: Hot water inlet
D: Hot water outlet
E: Recirculation air hole
F: Fresh air hole
G: Front air vents
H: Rear air vents
J: Foot level air vents
K: Defroster vents
1. Evaporator
2. Heater core
3. Expansion valve
4. Blower fan, blower motor
5. Air mix servomotor
6. Air mix door
7. Vent (mode) changeover servomotor
8. Rear door
9. Foot door
10. Defroster door
11. FRESH/RECIRC air changeover servomotor
12. FRESH/RECIRC air changeover servomotor
13.Power transistor
14. Evaporator temperature sensor
15. Inner sensor (inside air temperature sensor)
Outline
q The air conditioner unit consists of the evapora-
tor (1) and heater core (2), and is used to cool
down or warm up the air in the cab.
Temperature control
q Whenever a temperature control switch is oper-
ated on the machine monitor, temperature set-
ting data is sent to the air conditioner controller,
which is located behind the operator seat. The
air conditioner controller controls the air mix ser-
vomotor (5) and changes the angle of the air mix
door (6) in order to adjust the temperature.
Over-cooling (Freezing) prevention
q Evaporator temperature sensor (14) varies its
electrical resistance according to temperature.
The air conditioner controller detects the temper-
q
ature of the evaporator (1) by converting the
changes in the resistance of the evaporator tem-
perature sensor (14) into voltage changes.
The air conditioner controller performs control to
q
prevent freezing of the evaporator (1) by operat-
ing the compressor clutch relay (*) to stop the
compressor.
10
80-100
*: See "Parts and connectors layout" for details re-
garding the compressor clutch relay.
Air flow adjustment
q Whenever an air flow control switch is operated
on the machine monitor, air flow setting data is
sent to the air conditioner controller. The air con-
ditioner controller controls blower motor (4) us-
ing power transistor (13) in order to adjust the air
flow.
Vent (mode) changeover
q Whenever a vent switch is operated on the ma-
chine monitor, mode data is sent to the air con-
ditioner controller. The air conditioner controller
controls mode changeover servomotor (7) to ad-
just the opening angle of mode changeover
doors (8) to (10) and thus perform vent change-
over.
FRESH/RECIRC air changeover
q Whenever a FRESH/RECIRC air changeover
switch is operated on the machine monitor,
FRESH/RECIRC air changeover setting data is
sent to the air conditioner controller. The air con-
ditioner controller controls FRESH/RECIRC air
changeover servomotor (11) to open and close
FRESH/RECIRC air changeover door (12).
Automatic air conditioner
q Inside air temperature sensor (15) detects the in-
ternal temperature based on changes in resis-
tance. The air conditioner controller detects the
internal temperature by converting the changes
in the resistance of inside air temperature sensor
(15) into voltage changes.
The air conditioner controller checks the voltage
of inside air temperature sensor (15) and
controls the internal temperature so that it
matches the setting made on the machine
monitor.
Data from the sunlight sensor and the outside air
temperature sensor is also taken into consider-
ation when adjusting the internal temperature.
a The door is the same as the damper.
PC200, 200LC, 220, 220LC-8M0
100 Air conditioner
Air conditioner unit