engine overheat NISSAN PATROL 1998 Y61 / 5.G Heather And Air Conditioner Workshop Manual

Trouble Diagnoses for Abnormal Pressure
Whenever system's high or low-pressure side is abnormal, diagnose using a manifold gauge. The marker
above the gauge scale in the following table indicates the standard (normal) pressure range. Since the stan-
dard (normal) pressure differs from vehicle to vehicle, refer to HA-35 (``Ambient air temperature-to-operating
pressure table'').
Gauge indication Refrigerant cycle Probable cause Corrective action
Both high and low-pressure
sides are too high.
AC359A
+Pressure is reduced soon
after water is splashed on
condenser.Excessive refrigerant charge in
refrigeration cycle.Reduce refrigerant until speci-
®ed pressure is obtained.
Air suction by cooling fan is
insufficient.Insufficient condenser cooling
performance.
¯
j
1Condenser ®ns are clogged.
j
2Improper fan rotation of
cooling fan.+Clean condenser.
+Check and repair cooling fan
as necessary.
+Low-pressure pipe is not
cold.
+When compressor is stopped
high-pressure value quickly
drops by approximately 196
kPa (2.0 bar, 2 kg/cm
2,28
psi). It then decreases gradu-
ally thereafter.Poor heat exchange in con-
denser.
(After compressor operation
stops, high pressure decreases
too slowly.)
¯
Air in refrigeration cycle.Evacuate repeatedly and
recharge system.
Engine tends to overheat. Engine cooling systems mal-
function.Check and repair each engine
cooling system.
+An area of the low-pressure
pipe is colder than areas
near the evaporator outlet.
+Plates are sometimes cov-
ered with frost.+Excessive liquid refrigerant
on low-pressure side.
+Excessive refrigerant dis-
charge ¯ow.
+Expansion valve is open a
little compared with the
speci®cation.
¯
j
1Improper thermal valve
installation.
j
2Improper expansion valve
adjustment.Replace expansion valve.
High-pressure side is too high
and low-pressure side is too
low.
AC360A
Upper side of condenser and
high-pressure side are hot,
however, liquid tank is not so
hot.High-pressure tube or parts
located between compressor
and condenser are clogged or
crushed.+Check and repair or replace
malfunctioning parts.
+Check lubricant for contami-
nation.
TROUBLE DIAGNOSESMANUAL
HA-36