2008 Lexus GS350 Service & Repair Manual

2007-2011 Lexus GS350

HVAC Air Conditioning System (Service Information) - GS350/GS460 REFRIGERANT ON-VEHICLE INSPECTION ON-VEHICLE INSPECTION 1. INSPECT REFRIGERANT VOLUME Fig. 1: Identifying Sight Glass On Liquid Tube Sub - Assembly Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. a. Check the sight glass on the liquid tube sub-assembly A.

Test conditions:  Engine is running at 1, 500 RPM.  Blower speed control switch is at HI.  A/C switch is ON.  Temperature control switch is at the MAX. COOL position.  Doors are fully open. Item Symptom Amount of Refrigerant Corrective Procedures 1 Bubbles visible Insufficient * (1) Check for gas leakage and repair if necessary (2) 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 (1) Check for gas leakage with gas leak detector and repair if necessary (2) 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 (1) Drain or discharge refrigerant (2) Bleed air and supply proper amount of purified refrigerant Immediately

HINT: * : If the ambient temperature is higher than usual but cooling is sufficient, bubbles in the sight glass are permissible. 2. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET a. This method uses a manifold gauge set to locate problem areas. Read the manifold gauge pressure when these conditions are established. Test conditions:  Temperature at the air inlet is 30 to 35°C (86 to 95°F).  Engine is running at 1, 500 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: Refrigerant Pressure Graph 6 after A/C is turned OFF, refrigerant foams and then becomes clear Correct -

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. 1. Normally functioning refrigeration system Fig. 3: Identifying Gauge Reading - Normally Functioning Refrigeration System Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. Gauge reading 2. The A/C system periodically changes between normal and improper function due to moisture in the refrigerant system. Pressure side Refrigerant volume Low 0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm 2 ) High 1.37 to 1.57 MPa (14 to 16 kgf/cm 2 )

Fig. 4: Checking Refrigerant Pressure (Moisture In Refrigerant System) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. 3. The A/C system does not function effectively due to insufficient cooling. Fig. 5: Identifying Gauge Reading - Insufficient Cooling Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. Symptoms Probable Cause Diagnosis Corrective Actions 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 overly saturated - Moisture in refrigeration system freezes at expansion valve orifice and blocks refrigerant circulation 1. Replace cooler drier 2. Remove moisture from cycle by repeatedly evacuating air 3. Supply appropriate volume of new refrigerant Symptoms Probable Cause Diagnosis Corrective Actions - Pressure low 1. Check for gas leakage and repair if necessary 2. Supply appropriate

4. The A/C system does not function effectively due to poor circulation of the refrigerant. Fig. 6: Identifying Gauge Reading - Poor Circulation Of Refrigerant Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. 5. The A/C system does not function intermittently because the refrigerant does not circulate. on both low and high- pressure sides - Cooling performance insufficient Gas leakage from refrigeration system - Insufficient refrigerant - Refrigerant leakage volume of new refrigerant 3. If indicated pressure value close to 0 when connected to gauge, create vacuum after inspecting and repairing the location of leakage Symptoms Probable Cause Diagnosis Corrective Actions - 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

Fig. 7: Checking Refrigerant Pressure (Refrigerant Not Circulate) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. 6. The A/C system does not function effectively due to overcharged refrigerant or insufficient cooling of the condenser. Fig. 8: Checking Refrigerant Pressure (Overcharged Refrigerant Or Insufficient Cooling Of Condenser) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. Symptoms Probable Cause Diagnosis Corrective Actions - 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 1. Check expansion valve 2. Clean expansion valve by blowing air 3. Replace condenser 4. Evacuate air and charge appropriate volume of new refrigerant 5. For gas leakage from expansion valve, replace expansion valve Symptoms Probable Cause Diagnosis Corrective Actions - Condenser is 1. Clean condenser 2. Check condenser fan

7. The A/C system does not function due to air in the refrigeration system. Fig. 9: Checking Refrigerant Pressure (Air In Refrigeration System) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. 8. The A/C system does not function effectively due to an expansion valve malfunction. Pressure extremely high on both low and high- pressure sides - Excessive refrigerant - Cooling performance of condenser insufficient dirty - Condenser fan motor is malfunctioning - Excessive refrigerant motor operation 3. If 1 and 2 normal, check the amount of refrigerant and supply appropriate volume of refrigerant WARNING: The low-pressure piping may be very hot and cause serious burns. Symptoms Probable Cause Diagnosis Corrective Actions - 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 1. Check if compressor oil is dirty or insufficient 2. Evacuate air and charge new refrigerant

Fig. 10: Identifying Gauge Reading - Expansion Valve Malfunction Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. 9. The A/C system does not function due to a defective compressor. Fig. 11: Checking Refrigerant Pressure (Defective Compressor) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC. Symptoms Probable Cause Diagnosis Corrective Actions -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 Symptoms Probable Cause Diagnosis Corrective Actions -Pressure extremely high on both low and high- pressure sides -Pressure extremely low on high- Internal leakage in compressor - Compression failure - Leakage from damaged valve or broken sliding parts Repair or replace compressor

2008 Lexus GS350 Service & Repair Manual

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