REFRIGERANT ON-VEHICLE INSPECTION

PROCEDURE

1. INSPECT REFRIGERANT VOLUME (w/ Sight Glass)

   

   Text in Illustration

   *1	Sight Glass

   
   

   1. Check the sight glass on liquid tube sub-assembly B.

      Test conditions:

      
      

      • Engine running at 1500 rpm.

      • Blower speed control switch at HI.

      • A/C switch on.

      • Temperature control switch in MAX. COLD position.

      • All doors fully open.

      Item	Symptom	Amount of Refrigerant	Corrective Procedure
      1	Bubbles visible	Insufficient*	(1) Check for gas leakage and repair if necessary (2) Add refrigerant until bubbles disappear
      2	No bubbles visible	Empty, insufficient or excessive	Refer to items 3 and 4
      3	No temperature difference between compressor inlet and outlet	Empty or nearly empty	(1) Check for gas leakage with halogen leak detector and repair if necessary (2) Add refrigerant until bubbles disappear
      4	Considerable temperature difference between compressor inlet and outlet	Correct or much	Refer to items 5 and 6
      5	Immediately after A/C turned off, refrigerant becomes clear	Excessive	(1) Drain or discharge refrigerant (2) Bleed air and charge proper amount of purified refrigerant
      6	Immediately after A/C turned off, refrigerant foams and then becomes clear	Correct	-

      Tech Tips

      *: If the ambient temperature is higher than usual but cooling is sufficient, bubbles in the sight glass are permissible.

2. CHECK REFRIGERANT PRESSURE USING MANIFOLD GAUGE SET

   
   

   1. This is a method to identify trouble areas by using a manifold gauge set. Read the manifold gauge pressure under the following conditions.

      Test conditions:

      
      

      • Engine warm.

      • All doors fully open.

      • A/C switch on.

      • Blower speed control switch at HI.

      • Engine running at 1500 rpm.

      • Air inlet mode damper set at RECIRC.

      • Temperature control switch in MAX. COLD position.

      • Air temperature at air inlet 30 to 35°C (86 to 95°F).

      
      

      1. 

         When the refrigerant volume is correct, the gauge reading indicates as follows:

         Gauge Reading
         Pressure Side Specified Condition Low 0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2, 22 to 36 psi) High 1.37 to 1.57 MPa (14 to 16 kgf/cm2, 199 to 228 psi)

         Tech Tips

         Pressure varies in accordance with certain conditions (outside air temperature, sunlight and wind).

      2. When there is moisture in the refrigeration system:

         

         *1	Condition: Air conditioning system periodically cools and then fails to cool.

         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 temporary interruption of cycle However, when melted, returns to normal condition	Receiver dryer oversaturated Moisture in refrigeration system freezes at expansion valve orifice and blocks refrigerant circulation	Replace receiver dryer Remove moisture from cycle by repeatedly evacuating air Charge appropriate volume of new refrigerant

      3. When cooling is insufficient:

         

         *1	Condition: Air conditioning system does not function effectively.

         Symptom	Probable Cause	Diagnosis	Corrective Action
         Pressure low on both low and high pressure sides Bubbles are seen through sight glass continuously Cooling performance insufficient	Gas leakage from refrigeration system	Insufficient refrigerant Refrigerant leakage	Check for gas leakage using halogen leak detector, and repair if necessary Charge appropriate volume of new refrigerant If indicated pressure value close to 0 when connected to gauge, create vacuum after inspecting and repairing location of leakage

      4. When the circulation of the refrigerant is poor:

         

         *1	Condition: Air conditioning system does not function effectively.

         Symptom	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:

         

         *1	Condition: Air conditioning system does not function or functions intermittently.

         Symptom	Probable Cause	Diagnosis	Corrective Action
         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 with compressed air Replace condenser Evacuate air and then 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:

         

         *1	Condition: Air conditioning system does not function effectively.

         Symptom	Probable Cause	Diagnosis	Corrective Action
         Pressure extremely high on both sides No air bubbles are seen through sight glass even when engine rpm lowers	Excessive refrigerant Cooling performance of condenser insufficient	Excessive refrigerant Cooling performance of condenser insufficient	Clean condenser fins Check condenser fan motor operation by switching A/C ON If 1 and 2 normal, check amount of refrigerant and charge appropriate volume of refrigerant

      7. When there is air in the refrigeration system:

         

         *1	Condition: Air conditioning system does not function.
         *2	NOTE: These gauge indications occur when the refrigeration system opens and the refrigerant is supplied without performing vacuum purging.

         Symptom	Probable Cause	Diagnosis	Corrective Action
         Pressure extremely high on both low and high pressure sides Low pressure piping too hot to touch Bubbles can be seen through sight glass	Air in refrigeration system	Air in refrigeration system Insufficient vacuum purging	Check whether compressor oil dirty or insufficient Evacuate air and charge new refrigerant

      8. When the expansion valve malfunctions:

         

         *1	Condition: Air conditioning system does not function effectively.

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

      9. When the compressor is defective:

         

         *1	Condition: Air conditioning system does not function.

         Symptom	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 of compressor Leakage from damaged valve or broken sliding parts in compressor	Repair or replace compressor

3. INSPECT IDLING SPEED

   
   

   1. Warm up the engine.

   2. Inspect idling speed when these conditions are established.

      Standard
      for 1NR-FE
      Condition Idling Speed A/C switch off 550 to 650 rpm A/C switch on (A/C Lo → Hi) 700 → 850 rpm
      for 1ND-TV
      Condition Idling Speed A/C switch off 720 to 820 rpm A/C switch on (A/C Lo → Hi) 850 rpm Power heater switch on 950 rpm
      for 1NZ-FE
      Condition Idling Speed A/C switch off 550 to 650 rpm A/C switch on (A/C Lo → Hi) 700 → 850 rpm

      If the idling speed is not as specified, check the idle control system.