Operation and maintenance manual

Section 260-0130
SM 1405 Rev 2 11-04
11
air in the yellow supply hose, replacing the air with R-
134a. This is done in a few seconds. Tighten yellow
supply hose.
12. Open low side of R-134a gauges slowly. When
gauge reads zero open both sides completely.
Vacuum in the system will draw R-134a gas into the
system. Hold until both gauge readings equalize.
Note: Never charge with liquid R-134a. Charge on
the low pressure side only.
Final Charging Of The System
1. Start the engine and run at engine idle speed.
2. Turn the air conditioning system on with the
thermostat set on maximum cooling and fan on high
speed.
3. At this point a visual inspection must be made of
the sight glass on top of the receiver-drier. As
charging continues, the sight glass will appear milky
coloured as the bubbles in the system circulate. As
the system continues the charging process, the
regularity of the bubbles in the sight glass will
gradually diminish. When no bubbles are seen in the
sight glass, close the low pressure valve (blue side)
completely.
4. Increase the engine idle speed while observing the
sight glass. If many bubbles are seen resulting from
the increased engine speed, open the low pressure
side valve. Allow the system to continue the charging
procedure until the sight glass is clear. If the sight
glass remains clear, with the increased engine
speed, do not add any more R-134a.
Note: Occasionally bubbles are noticed during clutch
cycling or system start-up. This is a normal condition.
5. With the system completely charged, shut off the
engine. Close the valve on the R-134a canister and
remove the yellow supply hose. Remove both the low
pressure (blue) hose and high pressure (red) hose
from the filling ports on the compressor.
Note: Some R-134a will escape as the hoses are
being removed.
The system is completely charged when;
a. the sight glass is free from bubbles.
b. the suction pressure on the gauge is approx.
20 - 30 psig at 25° C ambient.
c. the correct weight of refrigerant has been added
(3.75 lbs.)
d. the correct superheat can be measured at the
evaporator, approx. 3 - 6° C.
e. the correct sub-cooling can be measured at the
condenser, approx. 5 - 7° C.
6. Replace protective caps on hoses and valve
fittings.
7. Lower hood assembly and remove wheel blocks.
SPECIAL TOOLS
Refer to Section 300-0070, SERVICE TOOLS, for
part numbers of special tools referenced in this
section and general service tools and sealants
required. These tools and sealants are available from
your dealer.
Operators Compartment - Air Conditioning