On-Vehicle Inspection

WARNING: This page is about a different car, the 2004 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT REFRIGERANT VOLUME

Observe the sight glass on the liquid tube.

Test conditions:

Engine speed at 1,500 RPM
Blower speed control switch at "HI" position
A/C switch ON
Temperature control dial at "COOL" position

Doors fully opened

Fig 1: Identifying Sight Glass

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM REFRIGERANT AMOUNT

Item

Symptom

Amount of refrigerant

Remedy

Bubbles appear in sight glass

Insufficient⁽¹⁾

Check for gas leakage with gas leak detector and repair, if necessary
Add refrigerant until bubbles disappear

No bubbles appear in sight glass

None, sufficient or too much

Refer to item 3 and 4

No temperature difference between compressor inlet and outlet

Empty or nearly empty

Check for gas leakage with gas leak detector and repair, if necessary
Add refrigerant until bubbles disappear

Temperature between compressor inlet and outlet is noticeably different

Correct or too much

Refer to items 5 and 6

Immediately after air conditioning system is turned off, refrigerant in sight glass stays clear

Too much

Discharge refrigerant
Evacuate air and charge proper amount of purified refrigerant

When air conditioning system is turned off, refrigerant foams and then stays clear

Correct

⁽¹⁾	Bubbles in the sight glass with ambient temperatures higher than usual can be considered normal if cooling is sufficient.

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

Check the trouble area using a set of manifold gauge set. Read the manifold gauge pressure when following conditions are detected.

Test conditions:

Temperature at the air inlet with the switch set at RECIRC is 30 - 35°C (86 - 95°F)
Engine speed at 2,000 RPM
Blower speed control switch at "HI" position
Temperature control dial on "COOL" position

HINT:

It should be noted that the gauge indications may vary depending on ambient temperature conditions.

Normally functioning refrigeration system.
Gauge reading:

Low pressure side:

0.15 - 0.25 MPa (1.5 - 2.5 kgf/cm ² )

High pressure side:

1.37 - 1.57 MPa (14-15 kgf/cm ² )

Fig 2: Identifying Gauges (1 Of 2)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Moisture present in refrigeration system.

Fig 3: Identifying Gauges (2 Of 2)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
During operation, pressure on low pressure side sometimes become a vacuum and sometime normal	Moisture entered in refrigeration system freezes at expansion valve orifice and temporarily stops cycle, but normal state is restored after a time when the ice melts	Drier in over-saturated state Moisture in refrigeration system freezes at expansion valve orifice and blocks circulation of refrigerant	Replace condenser Remove moisture in cycle through repeatedly evacuating air Charge proper amount of new refrigerant

Insufficient cooling

Fig 4: Insufficient Cooling Gauges

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Pressure low on both low and high pressure sides Bubbles seen in sight glass continuously Insufficient cooling performance	Gas leakage at some place in refrigeration system	Insufficient refrigerant in system Refrigerant leaking	Check for gas leakage with gas leak detector and repair if necessary Charge proper amount of refrigerant If indicated pressure value is near 0 when connected to gauge, create the vacuum after inspecting and repairing the location of the leak

Poor circulation of refrigerant

Fig 5: Identifying Poor Circulation Of Refrigerant Condition

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Pressure low in both low and high pressure sides Frost on tube from condenser to unit	Refrigerant flow obstructed by dirt in condenser	condenser clogged	Replace condenser

Refrigerant does not circulate

Fig 6: Identifying Refrigerant Circulate

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Vacuum indicated on low pressure side, very low pressure indicated on high pressure side Frost or dew seen on piping before and after condenser/drier or expansion valve	Refrigerant flow obstructed by moisture or dirt in refrigeration system Refrigerant flow obstructed by gas leakage from expansion valve	Refrigerant does not circulate	Check expansion valve Clean out dirt in expansion valve by blowing with air Replace condenser Evacuate air and charge new refrigerant to proper amount For gas leakage from expansion valve, replace expansion valve

Refrigerant overcharged or insufficient cooling of condenser

Fig 7: Identifying Refrigerant Overcharged Insufficient Cooling Condenser

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Pressure too high on both low and high pressure sides No air bubbles seen through the sight glass even when the engine rpm is lowered	Unable to develop sufficient performance due to excessive refrigeration system Insufficient cooling of condenser	Excessive refrigerant in cycle --> refrigerant over charged Condenser cooling --> condenser fins clogged of cooling fan faulty	Clean condenser Check cooling fan with fluid coupling operation If (1) and (2) are in normal state, check amount of refrigerant, and charge proper amount of refrigerant

Air present in refrigeration system

Fig 8: Identifying Air Present Refrigeration System

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Pressure too high on both low and high pressure sides The low pressure piping hot to touch Bubbles seen in sight glass	Air entered in refrigeration system	Air present in refrigeration system Insufficient vacuum purging	Check compressor oil to see if it is dirty or insufficient Evacuate air and charge new refrigerant

Expansion valve improperly

Fig 9: Identifying Expansion Valve

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Pressure too high on both low and high pressure sides Frost or large amount of dew on piping on low pressure side	Trouble in expansion valve	Excessive refrigerant in low pressure piping Expansion valve opened too wide	Check expansion valve, and replace if defective

Defective compression compressor

Fig 10: Identifying Defective Compression Compressor

SYMPTOM REFRIGERANT AMOUNT

Symptom seen in refrigeration system	Probable cause	Diagnosis	Remedy
Pressure too high on low and high pressure sides Pressure too low on high pressure side	Internal leak in compressor	Compression defective Valve leaking or broken sliding parts	Repair or replace compressor

INSPECT IDLE-UP SPEED

Warm up engine

Inspect idle-up speed when following conditions are established.

Test conditions:

Blower speed control switch at "HI" position
Temperature control dial at "COOL" position
A/C switch ON

Put gear shift in neutral

MAGNETIC CLUTCH CONDITION

Magnetic clutch condition	Idle-up speed
Magnetic clutch not engaged	750 +/- 50 rpm
Magnetic clutch engaged	780 +/- 50 rpm

If idle speed is not as specified, check the idle control system.

INSPECT FOR LEAKAGE OF REFRIGERANT
1. Perform in these conditions.
  - Stop engine
  - Secure good ventilation (The gas leak detector may not react to volatile gases which are not refrigerant, such as evaporated gasoline and exhaust gas)
  - Repeat the test 2 or 3 times
  - Make sure that there is some refrigerant remaining in the refrigeration system.
    When compressor is OFF: approx. 392 - 588 kPa (4-6 kgf-cm² , 57 - 85 psi)
2. Bring the gas leak detector close to the drain hose before performing the test.
  HINT:
  - After the blower motor stops, leave the cooling for more than 15 minutes.
  - Expose the gas leak detector sensor under the drain hose.
  - When bring the gas leak detector close to the drain hose, make sure that the gas leak detector does not react to the volatile gases.
    If gas leaks are detected, lift up the vehicle.
3. If gas leaks are not detected on the drain hose, remove the blower resistor from the cooling unit. Then insert the gas leak detector sensor into the unit to perform the test.
4. Disconnect the connector and leave the pressure switch for approx. 20 minutes. Then bring the gas leak detector close to the pressure switch to perform the test.
5. Bring the gas leak detector close to the refrigerant lines.