Case 580SR, Service Manual

Page: 788 / 1068

28 SECTION 50 - CAB HEATING AND AIR CONDITIONING
Attaching The Gauge Set To The Loader Backhoe
S WARNING
To avoid personal injury, stop the loader backhoe
engine during connection of the manifold gauge set.
1. Check that the gauge set shut off valves are
closed (turned fully clockwise).
2. Connect the high side gauge hose (normally
red) to the high pressure (discharge) side serv-
ice valve and the low side gauge hose (normally
blue) to the low pressure (suction) side service
valve on the loader backhoe. Ensure the hose
connections are fully tightened.
IMPORTANT: prior to connection of the manifold
gauge set, identify the suction (low pressure) and
discharge (high pressure) service gauge ports. The
high pressure service valve is always in the line from
the compressor to the condenser.
The high and low pressure service valves on the
loader backhoe are spring loaded valve and will be
automatically opened when the test hose is con-
nected.
NOTE: the test hose must incorporate a valve de-
pressor to actuate this type of valve.
The service valves have a protective cap. This cap
must be removed for test gauge connections and re-
placed when service operations are completed.
Test Procedure
After the manifold gauge set has been connected
and before pressure tests can be made, the system
must be stabilized as follows:
1. Apply the parking brake, check the gearshift le-
vers are in neutral and close the cab windows
and doors.
2. Re-check that both the high and low side shut
off valves on the manifold gauge set are fully
closed.
3. Run the engine at 1000-1200 rpm.
4. Turn the heater temperature control OFF.
5. Operate the system at maximum cooling, with
the blower fan at high speed for 10 minutes to
stabilize all components.
6. Check the manifold low pressure gauge reading
is within the specified range of approximately
0.28-2.48 bar.
7. Check the manifold high pressure gauge read-
ing and compare the reading to the pressure in-
dicated on the pressure temperature chart
below.
8. Measure and compare the temperature of con-
ditioned air entering the cab through the lou-
vered air vents with the ambient air at the air
intake filters on the outside of the cab.
If the system is operating correctly the condi-
tioned air entering the cab should be 6-9 °C
cooler than the ambient temperature of the out-
side air.
9. If it is confirmed that the system is not operating
correctly refer to the fault diagnostic charts and
performance test gauge reading examples on
the following pages for possible corrective ac-
tion.
S WARNING
A significant amount of refrigerant vapour may have
condensed to a liquid at the service fitting at the high
side of the compressor. Use a cloth or other protec-
tive material when disconnecting the manifold hose
from this fitting to prevent personal injury to hands
and face.
APPROXIMATE HIGH PRESSURE GAUGE READINGS
Ambient air temperature High pressure gauge reading
°C bar
27 10.0/11.6
29 11.2/12.7
32 12.3/13.8
35 13.3/15.2
38 14.5/16.7
41 16.0/18.3
43 17.3/20.0
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