Komatsu 830E, Shop Manual

Page: 572 / 783

M9-16 Air Conditioning System 05/02 M09010
for HFC 134a Refrigerant
Stabilizing the AC System
During this stabilization period, do not open hand
valves on manifold for any reason. Equipment
damage and personal injury may result.
1. Start the engine and return to an idle speed of
1200 to 1500 RPM. Turn on the air conditioner.
2. After a performance check of the control func-
tions, blower speeds and air flow, set the AC sys-
tem controls to maximum cooling and blower
speed on high. Open the cab to ensure continu-
ous operation of the compressor.
3. Run the engine and air conditioner about 5 min-
utes for the system to stabilize.
4. If the humidity is high it will be necessary to place
a fan in front of the AC condenser to help the air
flow across the condenser. This helps to stabilize
the system by simulating normal operating condi-
tions.
5. It is then possible to observe the gauge readings
and the temperature coming out of the air ducts
with a thermometer.
NOTE: If low refrigerant is indicated by lower than
normal pressure readings, recover and charge the
proper amount of refrigerant to enable adequate
system testing.
SYSTEM PERFORMANCE TEST
This test is performed to establish the condition of all
components in the system. Observe these conditions
during testing:
1. Start engine and operate at 1200 to 1500 RPM.
2. Place fan in front of condenser to simulate normal
ram air flow and allow system to stabilize.
3. Place a thermometer in air conditioning vent clos-
est to evaporator.
4. Evaluate the readings obtained from the gauges
to see if they match the readings for the ambient
temperature.
As preliminary steps to begin checkout of the system,
perform the following:
1. Close all windows and doors to the cab.
2. Set air conditioning system at maximum cooling
and blower speed operation.
3. Readings on the two manifold gauges should be
within normal range, adjust for ambient tempera-
ture.
4. Compare evaporator discharge air temperature
reading to see if it matches the recommended
temperature for the ambient temperature and
gauge readings obtained.
5. Carefully feel the hoses and components on the
high side. All should be warm-hot to the touch.
Check the inlet and outlet of receiver-drier for
even temperatures, if outlet is cooler than inlet, a
restriction is indicated.
Use extreme caution when placing hands on high
side components and hoses. Under certain condi-
tions these items can be extremely hot.
6. Feel the hoses and components on the low side.
They should be cool to the touch. Check connec-
tions near the expansion valve, inlet side should
be warm and cold-cool on the outlet side.
7. If these conditions are met, the system is consid-
ered normal. Shut down engine. Remove gauges
and install the caps on the service valves.