Refrigerant

Refrigerant
AC–12
AIR CONDITIONING – REFRIGERANT
REFRIGERANT
ON-VEHICLE INSPECTION
1.
AC
CHECK REFRIGERANT PRESSURE USING
MANIFOLD GAUGE SET
(a) This is a method to identify trouble areas by using a
manifold gauge set. Read the manifold gauge
pressure under the following conditions.
Test conditions:
• Engine warm.
• All doors fully open.
• A/C switch ON.
• Blower speed control switch at HI.
• Engine running at 1,500 rpm.
• Air inlet mode damper set at recirculation.
• Temperature control lever in MAX. COLD
position.
• Air temperature at air inlet 30 to 35°C (86 to
95°F).
E050573
(1) When the refrigerant volume is correct, the
gauge reading indicates as follows:
Low pressure side:
0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2)
High pressure side:
1.37 to 1.57 MPa (14 to 16 kgf/cm2)
HINT:
Pressure varies in accordance with certain
conditions (outside air temperature, sunlight
and wind).
(2) When there is moisture in the refrigeration
system:
Condition: Air conditioning system periodically
cools and then fails to cool.
I022117E03
Symptoms
Probable Cause
During operation, pressure on low
pressure side cycles between
normal and vacuum
Moisture in refrigeration system
freezes at expansion valve orifice,
causing temporary interruption of
cycle
However, when melted, returns to
normal condition
Diagnosis
•
•
Receiver dryer oversaturated
Moisture in refrigeration
system freezes at expansion
valve orifice and blocks
refrigerant circulation
Corrective Actions
1. Replace receiver dryer
2. Remove moisture from cycle
by repeatedly evacuating air
3. Supply appropriate volume of
new refrigerant
AC–13
AIR CONDITIONING – REFRIGERANT
(3) When cooling is insufficient:
Condition: Air conditioning system does not function effectively.
I022118E02
Symptoms
•
•
Pressure low on both low and
high pressure sides
Cooling performance
insufficient
Probable Cause
Gas leakage from refrigeration
system
Diagnosis
•
•
Insufficient refrigerant
Refrigerant leakage
Corrective Actions
1. Check for gas leakage using
gas leak detector, and repair
if necessary
2. Supply appropriate volume of
new refrigerant
3. If indicated pressure value
close to 0 when connected to
gauge, create vacuum after
inspecting and repairing
location of leakage
(4) When the circulation of the refrigerant is poor:
Condition: Air conditioning system does not function effectively.
I022119E02
Symptoms
•
•
Pressure low on both low and
high pressure sides
Frost exists on piping from
condenser to A/C unit
Probable Cause
Refrigerant flow obstructed by dirt
in condenser
Diagnosis
Condenser clogged
Corrective Action
Replace condenser
(5) When the refrigerant does not circulate:
Condition: Air conditioning system does not function or functions intermittently.
I022121E02
AC
AC–14
AIR CONDITIONING – REFRIGERANT
Symptoms
•
•
Vacuum indicated on low
pressure side, and extremely
low pressure indicated on
high pressure side
Frost or condensation seen
on piping on both sides of
condenser or expansion
valve
Probable Causes
•
•
Refrigerant flow obstructed
by moisture or dirt in
refrigeration system
Refrigerant flow obstructed
by gas leakage from
expansion valve
Diagnosis
Refrigerant does not circulate
Corrective Actions
1. Check expansion valve
2. Clean expansion valve with
compressed air
3. Replace condenser
4. Evacuate air and then supply
appropriate volume of new
refrigerant
5. For gas leakage from
expansion valve, replace
expansion valve
(6) When the refrigerant is overcharged or cooling
of condenser is insufficient:
Condition: Air conditioning system does not function effectively.
AC
I022121E03
Symptoms
Pressure extremely high on both
sides
Probable Causes
•
•
Excessive refrigerant
Cooling performance of
condenser insufficient
Diagnosis
•
•
Excessive refrigerant
Cooling performance of
condenser insufficient
Corrective Actions
1. Clean condenser fins
2. Check condenser fan motor
operation by switching A/C
ON
3. If 1 and 2 normal, check
amount of refrigerant and
supply appropriate volume of
refrigerant
(7) When there is air in the refrigeration system:
Condition: Air conditioning system does not function.
NOTE: These gauge indications occur
when the refrigeration system opens and
the refrigerant is supplied without
performing vacuum purging.
I022122E02
Symptoms
•
•
Pressure extremely high on
both low and high pressure
sides
Low pressure piping too hot
to touch
Probable Causes
Air in refrigeration system
Diagnosis
•
•
Air in refrigeration system
Insufficient vacuum purging
Corrective Actions
1. Check whether compressor
oil dirty or insufficient
2. Evacuate air and supply new
refrigerant
AC–15
AIR CONDITIONING – REFRIGERANT
(8) When the expansion valve malfunctions:
Condition: Air conditioning system does not function effectively.
I022123E02
Symptoms
•
•
Pressure extremely high on
both low and high pressure
sides
Frost or condensation on
piping on low pressure side
Probable Causes
Diagnosis
Expansion valve malfunction
•
•
Excessive refrigerant in low
pressure piping
Expansion valve opening too
wide
Corrective Actions
Replace expansion valve
AC
(9) When the compressor is defective:
Condition: Air conditioning system does not function.
I022124E02
Symptoms
•
•
Pressure extremely high on
both low and high pressure
sides
Pressure extremely low on
high pressure side
Probable Cause
Diagnosis
Internal leakage in compressor
•
•
2.
Compression failure of
compressor
Leakage from damaged valve
or broken sliding parts in
compressor
Corrective Actions
Repair or replace compressor
INSPECT IDLING SPEED
(a) Warm up the engine.
(b) Inspect the idling speed when these conditions are
established.
• Engine warm
• Blower speed control switch at HI
• Temperature control lever in MAX. COLD
position
Standard
Condition
Idling Speed
Switch A/C OFF
650 to 750 rpm
Switch A/C ON
750 to 850 rpm
If the idling speed is not as specified, check the idle
control system.
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