On-Vehicle Inspection

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

Check the sight glass of the cooler unit refrigerant liquid pipe E.

Set the vehicle according to the conditions below.

ITEM AND CONTENT REFERENCE

Item	Condition
All doors	Fully open
Temperature setting	MAX COLD
Blower speed	HI
A/C switch	ON

Fig 1: Identifying Sight Glass Of Cooler Unit Refrigerant Liquid Pipe E

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the sight glass under these conditions.

PROBLEM SYMPTOMS CHART

Item	Symptom	Amount of refrigerant	Corrective Actions
1	Bubbles exist	Insufficient*	Check for gas leakage and repair if necessary Add refrigerant until bubbles disappear
2	No bubbles exist (DTC 76 is output)	Empty, insufficient or excessive	Refer to 3 and 4
3	No temperature difference between compressor inlet and outlet	Empty or nearly empty	Check for gas leakage and repair if necessary Add refrigerant until bubbles disappear
4	Considerable temperature difference between compressor inlet and outlet	Proper or excessive	Refer to 5 and 6
5	Immediately after air conditioning is turned off, refrigerant remains clear	Excessive	Discharge refrigerant Remove air and supply proper amount of purified refrigerant
6	Immediately after air conditioning is turned off, refrigerant foams and then becomes clear	Proper	-

HINT:

Bubbles in the sight glass with the room temperature higher than usual can be considered normal if cooling is sufficient.

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

This is a method in which the trouble is located by using a manifold gauge set. Read the manifold gauge pressure when these conditions are established.

Gauge readings (Reference) Test conditions:

Temperature at the air inlet with the switch set at RECIRC is 30 to 35°C (86 to 95°F)
Blower speed control switch at "HI" position
Temperature control switch at "MAX COLD" position
A/C switch ON
Fully open doors

The refrigeration system functions normally Gauge reading:
Low-pressure side: 0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm ² )

High-pressure side: 1.37 to 1.57 MPa (14 to 16 kgf/cm ² )

Moisture present in refrigeration system

Fig 2: Identifying Manifold Gauge Set

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
During operation, pressure on low-pressure side cycles between normal and vacuum	Moisture in refrigerating system freezes at expansion valve orifice, causing a temporary stop of cycle. However, when it melts, normal state is restored.	- Cooler dryer in oversaturated state Moisture in refrigeration system freezes at expansion valve orifice and blocks circulation of refrigerant	Replace cooler dryer Remove moisture in cycle by repeatedly evacuating air Supply proper amount of new refrigerant

Insufficient cooling

Fig 4: Checking Refrigerant Pressure (Insufficient Cooling)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure is low on both low and high-pressure sides Bubbles are continuously seen through sight glass Insufficient cooling performance	Gas leakage in refrigeration system	Insufficient refrigerant Refrigerant leaking	Check for gas leakage and repair if necessary Supply proper amount of new refrigerant If the indicated pressure value is close to 0 when connected to the gauge, create a vacuum after inspecting and repairing location of leakage

Poor circulation of refrigerant

Fig 5: Checking Refrigerant Pressure (Poor Circulation Of Refrigerant)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure low on both low and high-pressure sides Frost exists on pipe from cooler condenser to A/C unit	Refrigerant flow is obstructed by dirt in cooler condenser core	Cooler condenser core is clogged	Replace cooler condenser core

Refrigerant does not circulate

Fig 6: Checking Refrigerant Pressure (Refrigerant Not Circulate)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Vacuum is indicated on low-pressure side and very low pressure is indicated on high-pressure side Frost or condensation is seen on piping on both sides of cooler condenser core or expansion valve	Refrigerant flow is obstructed by moisture or dirt in refrigeration system Refrigerant flow obstructed by gas leaked from cooler expansion valve	Refrigerant does not circulate	Check expansion valve Clean out dirt in cooler expansion valve by blowing air Replace cooler condenser core Evacuate and charge new refrigerant For gas leakage from cooler expansion valve, replace cooler expansion valve

Refrigerant overcharged or insufficient cooling of condenser

Fig 7: Checking Refrigerant Pressure (Refrigerant Overcharged)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure is too high on both low and high-pressure sides No air bubbles are seen through the sight glass when compressor speed decreases	Excessive refrigerant Insufficient cooling of cooler condenser core	Excessive refrigerant in cycle (excessive refrigerant is supplied) Insufficient cooling of cooler condenser core	Clean cooler condenser core fins Check cooling fan with condenser fan motor operation If 1 and 2 normal, check the amount of refrigerant and supply proper amount of refrigerant

Air present in refrigeration system

Fig 8: Checking Refrigerant Pressure (Air Present In Refrigeration System)

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure is too high on both low and high-pressure sides Low-pressure piping is too hot to touch Bubbles are seen through sight glass	Air in system	Air present in refrigeration system Insufficient vacuum purging	Check compressor oil to see if it is dirty or insufficient Evacuate and charge new refrigerant

Expansion valve malfunction

Fig 9: Checking Refrigerant Pressure (Expansion Valve Malfunction)

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure is too high on both low and high-pressure sides Frost or large amount of condensation on piping on low-pressure side	Trouble in cooler expansion valve	Excessive refrigerant in low pressure piping Cooler expansion valve is opened too wide	Replace cooler expansion valve

Defective compression in compressor

Fig 10: Checking Refrigerant Pressure (Defective Compression In Compressor)

PROBLEM SYMPTOMS CHART

Symptoms	Probable Cause	Diagnosis	Corrective Actions
Pressure is too high on both low and high-pressure sides Pressure is too low on high-pressure side	Internal leak in cooler compressor	Compression failure Leakage from damaged valve or broken sliding parts	Repair or replace compressor

Gauge readings (Reference)

Fig 11: Refrigerant Pressure Graph