24
4 - TROUBLESHOOTING
A/C cycle diagnosis by gauge pressure
Following is a diagnosis procedure to connect gauge manifold to A/C cycle, measure suction and
discharge pressures and analyze the defects of the cycle.
Operation conditions of the A/C cycle for pressure measuring:
1. Ambient temperature: 30 - 35 °C
2. Engine speed: 1,500 rpm
3. A/C switch: ON
4. Blower speed: high
5. Temperature control: full cold
Gauge pressure
indication
Cause
Confirmation method
Action to take
Pressure is normal
A/C cycle operates normally. If there is any defect (poor cooling
performance), there shall be another cause.
●
Discharge pressure
: around 0.9 - 1.6 MPaG (10 - 17 kgf/cm²)
●
Suction pressure
: around 0.03 - 0.10 MPaG (1.3 - 2.0 kgf/cm²)
Both discharge and
suction pressures are
low
Refrigerant shortage
Connect gauge
manifold to cycle
Recover refrigerant,
then refill with the right
amount of refrigerant
Receiver dryer is
clogged
Temperature difference
between inlet and outlet
pipes happens. Dryer is
covered with frost
Replace parts
Expansion valve is
clogged
Expansion valve was
covered with frost or
dust
Clean or replace part
(Tightening torque = 7.8~9.8N.m)
Enclosure leakage from
the expansion valve
temperature sensing
tube. (Expansion valve
operates to close the
valve opening)
Outlet side of the
expansion valve is not
cooling. (Low side of
gauge indicates
vacuum)
Replace part
Temperature sensing
device at outlet air is
defective
Evaporator becomes
frozen up
Adjust or replace the
part
Refrigerant piping is
clogged or crashed
If any part between the
dryer and the
compressor is clogged
or crashed, the low side
pressure becomes
vacuum
Adjust or replace the
part
