Mitsubishi Lancer (4A9 engine). Manual - part 302
ON-VEHICLE SERVICE
HEATER, AIR CONDITIONER AND VENTILATION
55A-89
DIAGNOSIS BY REFRIGERANT
PRESSURE
M1552023000184
A/C
system
symptom
Measurement circumstance
Cause
Measures
Hig
h
pres
sure
Low
pres
sure
Air
outl
et
tem
pera
ture
Note
Cooler is
not
effective.
Low High High
• Pressure for low
pressure side is high,
and high pressure
side is low.
• When the A/C
operation is stopped,
the pressures of low
pressure side and
high pressure side
immediately become
identical.
• Leakage inside
compressor
• Faulty
compression of
compressor
1. Check according to the
compressor check.
1. When no foreign object
is present to the oil, and
when the colour is light
grey, replace only the
compressor.
2. When foreign objects
are mixed to the oil, and
the colour is black,
replace the compressor
and receiver.
2. Perform the evacuation
sufficiently to remove the
foreign objects and
moisture in the cycle.
3. Fill the new gas to the
specified amount.
High High High
• Low pressure side/
high pressure side
pressure is too high.
• Low pressure side
piping is too hot to
touch.
• Air is mixed to
the refrigerant
cycle.
• Evacuation is
insufficient.
1. Perform the evacuation
sufficiently, and remove
the foreign objects and
moisture in the cycle.
2. Fill the new gas to the
specified amount.
Sufficient
cooling and
insufficient
cooling
occur
periodically.
Fluc
tuati
on
Fluc
tuati
on
Fluc
tuati
on
During the air
conditioner operation,
the low pressure side
pressure alternates
between the negative
pressure and normal.
(also in the high
pressure side, the
abnormal and normal
statuses are alternated).
The moisture in
the refrigerant
cycle becomes
frozen in the
expansion valve,
then the
circulation of
refrigerant is
stopped
temporarily.
Subsequently, the
status recovers to
normal by the
melting of ice.
1. Replace the receiver
(drier).
2. Perform the evacuation
sufficiently, and remove
the moisture in the cycle.
3. Fill the new refrigerant to
the specified amount.