Toyota T100 1996 Service Manual page 1975

AC−4
Condition : Periodically cools and then fails to cool
Symptom seen in
refrigeration system
During operation, pressure on low
pressure side sometimes become
a vacuum and sometime normal
1996 TOYOTA T100 (RM449U)
AIR CONDITIONING
2.
This is a method in which the trouble is located by using a man-
ifold gauge set. Read the manifold gauge pressure when these
conditions are established.
HINT:
It should be noted that the gauge indications may vary slightly
due to ambient temperature conditions.
I01386
Probable cause
Moisture entered in refrigeration
system freezes at expansion valve
orifice and temporarily stops cycle,
but normal state is restored after a
time when the ice melts
− AIR CONDITIONING SYSTEM
INSPECT REFRIGERANT PRESSURE WITH MAN-
IFOLD GAUGE SET
Test conditions:
Temperature at the air inlet with the switch set
S
at RECURC is 30 − 35 °C (86 − 95 °F)
Engine running at 1500 rpm
S
Blower speed control switch on "HI" position
S
Temperature control dial on "COOL" position
S
(1) Normally functioning refrigeration system.
Gauge reading:
Low pressure side:
0.15 − 0.25 MPa (1.5 − 2.5 kgf/cm
High pressure side:
1.37 − 1.57 MPa (14 − 16 kgf/cm
(2) Moisture present in refrigeration system.
Diagnosis
S Drier in oversaturated state
S Moisture in refrigeration system
freezes at expansion valve orifice
and blocks circulation of refriger-
ant
2
)
2)
Remedy
(1) Replace receiver
(2) Remove moisture in cycle
through repeatedly evacuating air
(3) Charge proper amount of new
refrigerant
I01387