On-Vehicle Inspection

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT REFRIGERANT VOLUME

Check the sight glass on the liquid tube sub-assembly.

Test conditions:

Engine is running at 1500 rpm.
Blower speed control switch is at HI
A/C switch is ON.
Temperature control switch is at MAX COOL
Doors are fully open.

Fig 1: Identifying Sight Glass On Liquid Tube Sub-Assembly
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

AMOUNT OF REFRIGERANT

Item	Symptom	Amount of Refrigerant	Corrective Procedure
1	Bubbles visible	Insufficient	Check for gas leakage and repair if necessary Add refrigerant until bubbles disappear
2	No bubbles visible	Empty, insufficient or too much	Refer to items 3 and 4
3	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
4	Considerable temperature difference between compressor inlet and outlet	Correct or too much	Refer to items 5 and 6
5	Immediately after A/C is turned OFF, refrigerant becomes clear	Too much	Drain or discharge refrigerant Bleed air and supply proper amount of purified refrigerant
6	Immediately after A/C is turned OFF, refrigerant foams and then becomes clear	Correct	-

HINT.

If the ambient temperature is higher than usual but cooling is sufficient, bubbles in the sight glass are permissible.

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

This method uses a manifold gauge set to locate problem areas. Read the manifold gauge pressure when the following conditions are established Test conditions:

Temperature at the air inlet is 30 to 35°C (86 to 95°F).
Engine is running at 1500 rpm
All doors are fully open
Blower speed control switch is at HI.
Temperature control switch is at MAX COOL.
A/C switch is ON

Gauge readings (Reference)

Fig 2: Identifying Refrigerant Pressure Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Normally functioning refrigeration system

Gauge Reading

GAUGE READING

Pressure Side	Refrigerant Volume
Low	0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm² )
High	1.37 to 1.57 MPa (14 to 16 kgf/cm² )

The A/C system periodically changes between normal and improper function due to moisture in the refrigeration system.

Fig 3: Identifying Refrigerant Pressure Gauge

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 4: Refrigerant Pressure Gauge Reading For Normal And Improper Function Due To Moisture In Refrigeration System

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
During operation, pressure on low - pressure side cycles between normal and vacuum	Moisture in refrigeration system freezes at expansion valve orifice, causing temporary stop of cycle However, when melted, normal state is restored	Drier is oversaturated Moisture in refrigeration system freezes at expansion valve orifice and blocks refrigerant circulation	Replace cooler drier Remove moisture from cycle by repeatedly evacuating air Supply appropriate volume of new refrigerant

The A/C system does not function effectively due to insufficient cooling

Fig 5: Refrigerant Pressure Gauge Reading For A/C System Does Not Function Effectively Due To Insufficient Cooling

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
Pressure low on both low and high-pressure sides Cooling performance insufficient	Gas leakage from refrigeration system	Insufficient refrigerant Refrigerant leakage	Check for gas leakage and repair if necessary Supply appropriate volume of new refrigerant If indicated pressure value is close to 0 when connected to gauge, create vacuum after inspecting and repairing the location of leakage

The A/C system does not function effectively due to poor circulation of the refrigerant.

Fig 6: Refrigerant Pressure Gauge Reading For Poor Circulation Of Refrigerant

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
Pressure low on both low and high-pressure sides Frost exists on piping from condenser to A/C unit	Refrigerant flow obstructed by dirt in condenser	Condenser clogged	Replace condenser

The A/C system does not function intermittently because the refrigerant does not circulate.

Fig 7: Refrigerant Pressure Gauge Reading For Refrigerant Does Not Circulate

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
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	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 expansion valve by blowing air Replace condenser Evacuate air and charge appropriate volume of new refrigerant For gas leakage from expansion valve, replace expansion valve

The A/C system does not function effectively due to overcharged refrigerant or insufficient cooling of the condenser

Fig 8: Refrigerant Pressure Gauge Reading For Refrigerant Or Insufficient Cooling Of Condenser

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
Pressure extremely high on both low and high-pressure sides	Excessive refrigerant Cooling performance of condenser insufficient	Condenser is dirty Condenser fan motor is malfunctioning Excessive refrigerant	Clean condenser Check condenser fan motor operation If 1 and 2 are normal, check the amount of refrigerant and supply appropriate volume of refrigerant

The A/C system does not function due to air in the refrigeration system

CAUTION: The low-pressure piping may be very hot and cause serious burns.

Fig 9: Refrigerant Pressure Gauge Reading For Refrigeration System

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
Pressure extremely high on both low and high-pressure sides The low-pressure piping is too hot to touch	Air in refrigeration system	Air in refrigeration system Vacuum purging insufficient	Check if compressor oil is dirty or insufficient Evacuate air and charge new refrigerant

The A/C system does not function effectively due to an expansion valve malfunction.

Fig 10: Refrigerant Pressure Gauge Reading For Expansion Valve Malfunction

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
Pressure extremely high on both low and high-pressure sides Frost or condensation on piping on low-pressure side	Problem with expansion valve	Excessive refrigerant in low pressure piping Expansion valve too wide open	Replace expansion valve

The A/C system does not function due to a defective compressor

Fig 11: Refrigerant Pressure Gauge Reading For Defective Compressor

SYMPTOM CHART

Symptom	Probable Cause	Diagnosis	Corrective Action
Pressure extremely high on both low and high-pressure sides Pressure extremely low on high-pressure side	Internal leakage in compressor	Compression failure Leakage from damaged valve or broken sliding parts	Repair or replace compressor