Owner's Manual

INSUFFICIENT COOLING
MTC-61
C
D
E
F
G
H
I
K
L
M
A
B
MTC
Trouble Diagnoses for Abnormal Pressure EJS001BA
Whenever system's high and/or low side pressure is abnormal, diagnose using a manifold gauge. The marker
above the gauge scale in the following tables indicates the standard (normal) pressure range. However, since
the standard (normal) pressure differs from vehicle to vehicle, refer to MTC-60, "
Ambient Air Temperature-to-
Operating Pressure Table" .
BOTH HIGH AND LOW-PRESSURE SIDES ARE TOO HIGH.
HIGH-PRESSURE SIDE IS TOO HIGH AND LOW-PRESSURE SIDE IS TOO LOW.
Gauge indication Refrigerant cycle Probable cause Corrective action
Both high and low-pressure sides
are too high.
● Pressure is reduced soon
after water is splashed on
condenser.
Excessive refrigerant charge
in refrigeration cycle
Reduce refrigerant until speci-
fied pressure is obtained.
Air suction by cooling fan is
insufficient.
Insufficient condenser cooling
performance
↓
1. Condenser fins are
clogged.
2. Improper 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
kg/cm
2
, 28 psi). It then
decreases gradually there-
after.
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 flow
● Expansion valve is open a
little compared with the
specification.
↓
1. Improper thermal valve
installation
2. Improper expansion valve
adjustment
Replace expansion valve.
AC359A
Gauge indication Refrigerant cycle Probable cause Corrective action
High-pressure side is too high and
low-pressure side is too low.
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.
AC360A