On-Vehicle Inspection

WARNING: This page is about a different car, the 2008 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

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.
A/C switch is ON.

Gauge readings (Reference).

Fig 1: Identifying Blower Zone Graph - Pressure

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Normally functioning refrigeration system

Fig 2: Identifying Manifold Gauge Set Different Position

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Gauge reading

PRESSURE SIDE REFRIGERANT VOLUME CHART

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 refrigerant system.

Fig 3: Checking Refrigerant Pressure (Moisture In Refrigerant System)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOMS CHART

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	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 4: Checking Refrigerant Pressure (Insufficient Cooling)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
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 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 5: Checking Refrigerant Pressure (Poor Circulation Of Refrigerant)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOMS CHART

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

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

Fig 6: Checking Refrigerant Pressure (Refrigerant Not Circulate)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOMS CHART

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	Check expansion valve refrigerant 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 7: Checking Refrigerant Pressure (Overcharged Refrigerant Or Insufficient Cooling Of Condenser)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
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 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 8: Identifying Manifold Gauge Set Different Position

SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure extremely high on both low and high-pressure sides 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 9: Checking Refrigerant Pressure (Expansion Valve Malfunction)

SYMPTOMS CHART

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

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

Fig 10: Checking Refrigerant Pressure (Defective Compressor)

SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
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