REFRIGERANT ON-VEHICLE INSPECTION


  1. INSPECT REFRIGERANT VOLUME


    1. A01BHY3E01

      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 Action
      1 Bubbles exist Insufficient*

      1. Check for gas leakage and repair if necessary

      2. Add refrigerant until bubbles disappear
      2 No bubbles exist Empty, insufficient or excessive Refer to 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 Proper or excessive Refer to 5 and 6
      5 Immediately after air conditioning is turned off, refrigerant clears Excessive

      1. Discharge refrigerant

      2. Remove air and supply proper amount of purified refrigerant
      6 Immediately after air conditioning is turned off, refrigerant foams and then becomes clear Proper -

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

  2. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


    1. This is a method in which the trouble is located by using a manifold gauge set. Read the manifold gauge pressure when the following 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 1,500 rpm.

      • Blower speed control switch is at "HI".

      • Temperature control dial is at "COOL".

      • A/C switch is on.

      • Doors are fully open.


      1. A01BBQJ

        Refrigerant system functions normally.

        Gauge reading
        Low pressure side
        0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2, 21.3 to 35.6 psi)
        High pressure side
        1.37 to 1.57MPa (14 to 16 kgf/cm2, 199 to 228 psi)

      2. Moisture present in refrigeration system.

        A01BB4TE06
        Symptom Probable cause Diagnosis Corrective Action
        During operation, pressure on low pressure side cycles between normal and vacuum Moisture in refrigeration system freezes at expansion valve orifice, causing a temporary stop of cycle. However, when it melts, normal state is restored.

        • Drier in oversaturated state

        • Moisture in refrigeration system freezes at expansion valve orifice and blocks circulation of refrigerant

        1. Replace condenser

        2. Remove moisture in cycle by repeatedly evacuating air

        3. Supply a proper amount of new refrigerant

      3. Insufficient cooling

        A01BEOYE03
        System Probable cause Diagnosis Corrective Action

        • Pressure is low on both low and high pressure sides

        • Bubbles are seen through sight glass continuously

        • Insufficient cooling performance

        		 Gas leakage in refrigeration system

        • Insufficient refrigerant

        • Refrigerant leaking

        1. Check for gas leakage and repair if necessary

        2. Supply a proper amount of new refrigerant

        3. If the indicated pressure value is close to 0 when connected to the gauge, create a vacuum after inspecting and repairing the location of leakage.

      4. Poor circulation of refrigerant

        A01BFL0E03
        System Probable cause Diagnosis Corrective Action

        • Pressure is low on both low and high pressure sides

        • Frost exists on pipe from condenser to unit

        		 Refrigerant flow is obstructed by dirt in the receiver Receiver is clogged Replace condenser

      5. Refrigerant does not circulate.

        A01BGY9E02
        System Probable cause Diagnosis Corrective Action

        • 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 receiver/drier or expansion valve

        • Refrigerant flow is obstructed by moisture or dirt in refrigeration system

        • Refrigerant flow is obstructed by gas leak from expansion valve

        		 Refrigerant does not circulate

        1. Check the expansion valve

        2. Replace condenser

        3. Evacuate air and supply a proper amount of new refrigerant

        4. For gas leakage from expansion valve, replace expansion valve

      6. Refrigerant is overcharged or cooling effectiveness of condenser is insufficient.

        A01BHDJE04
        System Probable cause Diagnosis Corrective Action

        • Pressure is too high on both low and high pressure sides

        • No air bubbles are seen through sight glass even when engine rpm lowers

        • Unable to develop sufficient performance due to excessive charging of refrigeration system

        • Cooling effectiveness of condenser is insufficient.

        • Excessive refrigerant in cycle → excessive refrigerant is supplied

        • Condenser cooling effectiveness in insufficient → condenser fins are clogged at cooling fan

        1. Clean condenser

        2. Check cooling fan with cooling fan motor operated

        3. If 1. and 2. are normal, check the amount of refrigerant and supply a proper amount of refrigerant

      7. Air is present in refrigeration system.

        A01BAKBE07
        System Probable cause Diagnosis Corrective Action

        • Pressure is too high on both low and high pressure sides

        • The low pressure piping is too hot to touch

        • Bubbles can be seen through sight glass

        		 Air in system

        • Air present in refrigeration system

        • Insufficient purging

        1. Check compressor oil to see if it is dirty or insufficient

        2. Vacuum and supply new refrigerant

      8. Expansion valve malfunction

        A01BFTVE03
        System Probable cause Diagnosis Corrective Action

        • Pressure is too high on both low and high pressure sides

        • Frost or a large amount of condensation is on piping on low pressure side

        		 Trouble in expansion valve

        • Excessive refrigerant in low pressure piping

        • Expansion valve opened too wide

        		 Check expansion valve

      9. Defective compressor

        A01BBSME03
        System Probable cause Diagnosis Corrective Action

        • Pressure is too high on both low and high pressure sides

        • Pressure is too low on high pressure side

        		 Internal leak in compressor

        • Compression failure

        • Leakage from damaged valve or broken sliding parts

        		 Repair or replace compressor

        • Gauge readings (Reference)

        A01BC4DE07