On-Vehicle Inspection

INSPECT REFRIGERANT VOLUME

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

Test conditions.

Temperature at the air inlet is 30 to 35°C (86 to 95°F).
Engine is running at 1500 rpm (see INSPECTION MODE PROCEDURE ).
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.

Fig 1: Identifying Sight Glass On Liquid Tube

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

REFRIGERANT VOLUME - ITEM SYMPTOM CHART

Item	Symptom	Amount of Refrigerant	Corrective Procedures
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 halogen 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	Dram 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 these conditions are established Test conditions

Temperature at the air inlet with the switch set at RECIRC is 30 to 35°C (86 to 95°F).
Engine is running at 1500 rpm (see INSPECTION MODE PROCEDURE )
All doors are fully open
Blower speed control switch is at HI.
A/C switch is ON

Gauge readings (Reference)

Fig 2: Refrigerant Pressure Chart With Manifold Gauge Set

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Normally functioning refrigeration system

Gauge reading

REFRIGERANT VOLUME SPECIFICATION

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 - Normally Functioning

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 4: Checking Refrigerant Pressure - Moisture In Refrigerant System

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

MOISTURE IN REFRIGERANT SYSTEM - PROBLEM SYMPTOM 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 5: Checking Refrigerant Pressure - Insufficient Cooling

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSUFFICIENT COOLING - PROBLEM SYMPTOM 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 6: Checking Refrigerant Pressure - Poor Circulation Of Refrigerant

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

POOR CIRCULATION OF REFRIGERANT - PROBLEM SYMPTOM 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 or functions intermittently because the refrigerant does not circulate.

Fig 7: Checking Refrigerant Pressure - Refrigerant Does Not Circulate

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

REFRIGERANT DOES NOT CIRCULATE - PROBLEM SYMPTOM 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 8: Checking Refrigerant Pressure - Overcharged Refrigerant Or Insufficient Cooling

OVERCHARGED REFRIGERANT OR INSUFFICIENT COOLING - PROBLEM SYMPTOM 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 9: Checking Refrigerant Pressure - Air In Refrigeration System

AIR IN REFRIGERATION SYSTEM - PROBLEM SYMPTOM 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 10: Checking Refrigerant Pressure - Expansion Valve Malfunction

EXPANSION VALVE - PROBLEM SYMPTOM 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 11: Checking Refrigerant Pressure - Defective Compressor

DEFECTIVE COMPRESSOR - PROBLEM SYMPTOM 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