Heater Components - Komatsu 830E Shop Manual

HEATER/AIR CONDITIONER
The heater assembly incorporates all the controls nec-
essary for regulating the cab interior temperature;
heated air during cold weather operation and cooled,
de-humidified air during warm weather operation if the
optional air conditioning system is installed.
The following information primarily describes the
heater system. Refer to Section M, "Air Conditioning
System" for detailed information concerning the com-
plete air conditioning system operation, repair, and
system recharging instructions.
OPERATION
Heat for the cab is provided by passing coolant from
the engine cooling system through a heater core.
Blowers move air across the heating core which
warms the air for heating or defrosting.
An engine driven freon compressor passes air condi-
tioning system refrigerant through an evaporator core
mounted in the same enclosure. The same blowers
used for heating move air across the evaporator to
provide cooled air through the outlet vents.
All heater and air conditioner controls are mounted on
a pod on the face of the enclosure.
N04023

HEATER COMPONENTS

Figures 4-3 and 4-4 illustrate both the heater system
and air conditioning system parts contained in the cab
mounted enclosure. Refer to Section "M" for additional
information regarding air conditioning system compo-
nents, maintenance and repair.
CIRCUIT BREAKERS
Before attempting to troubleshoot the electrical circuit
in the heater enclosure, turn key switch ON and verify
circuit breaker CB31 (located on Power Distribution
Module behind operator's seat) and the internal heater
circuit breaker have not opened by verifying +24VDC
is present on the junction block (38, Figure 4-4).
RELAYS
There are five relays (9, Figure 4-3) that control the air
dampers, A/C compressor and the heater valve. All
five relays require 12 volts D.C. through the coil which
is supplied by a 24VDC - 12VDC converter (2).
One relay (Relay 1) switches 24 volt current to actuate
the A/C compressor clutch. The temperature control
switch, heater valve and the actuator motors all oper-
ate on 12 volts D.C. current.
FIGURE 4-3. CAB HEATER/AIR CONDITIONER
1. Enclosure
2. Converter (24 V to 12 V)
3. Water Control (Heater) Valve
4. A/C Freon Hoses
5. Water Outlet (To Engine)
6. Water Inlet (From Engine Water Pump)
7. Evaporator Core
8. Heater Core
9. Relays
Operator Comfort
COMPONENTS
N4-3