On-Vehicle Inspection

Test conditions:

• Engine has been warmed up.
• All doors are fully open.
• A/C switch is ON.
• Engine is running at 1,500 rpm.
• Air inlet mode selector damper is set at recirculation.
• Temperature control switch is in MAX. COLD position.
• Blower speed control switch is in HI position.
• Air temperature at the air inlet is 30 to 35°C (86 to 95°F).

Gauge readings (Reference)

Fig 1: Pressure Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. When the refrigerant volume is proper:

   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  ) 

   Fig 2: Checking Refrigerant Pressure (1 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. When there is moisture in the refrigeration system:
   Fig 3: Checking Refrigerant Pressure (2 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

   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 restored	Drier 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

3. When cooling is insufficient:
   Fig 4: Checking Refrigerant Pressure (3 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

   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

4. When the circulation of the refrigerant is poor:
   Fig 5: Checking Refrigerant Pressure (4 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

   Symptoms	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

5. When the refrigerant does not circulate:
   Fig 6: Checking Refrigerant Pressure (5 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

   Symptoms	Probable Causes	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 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

6. When the refrigerant is overcharged or cooling of condenser is insufficient:
   Fig 7: Checking Refrigerant Pressure (6 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

   Symptoms	Probable Causes	Diagnosis	Corrective Actions
   Pressure extremely high on both low and high pressure sides	Excessive refrigerant Cooling performance of condenser insufficient	Excessive refrigerant Cooling performance of condenser insufficient	Clean condenser Check condenser fan motor operation If 1 and 2 normal, check the amount of refrigerant and supply appropriate volume of refrigerant

7. When there is air in the refrigeration system:
   Fig 8: Checking Refrigerant Pressure (7 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

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

8. When the expansion valve malfunctions:
   Fig 9: Checking Refrigerant Pressure (8 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

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

9. When the compressor is defective:
   Fig 10: Checking Refrigerant Pressure (9 Of 9)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   PROBABLE CAUSE SYMPTOM TABLE
   
   

   Symptoms	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