REFRIGERANT > ON-VEHICLE INSPECTION

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1. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

HINT:
The following examples show the readings of a manifold gauge set and the corresponding air conditioning system problems.



  1. Read the manifold gauge pressure when the following conditions are met:

    1. Temperature at the air inlet with recirculate selected is 30 to 35°C (86 to 95°F).
    2. The blower speed is set to high.
    3. The temperature is set to max cool.
    4. The A/C switch is on.
    5. Doors are fully open.
    6. The power switch is on (READY).



      E050573

    1. Normally functioning air conditioning system.
      Gauge Reading 
      Pressure Side
      		Refrigerant Volume
      Low
      		0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2, 21 to 36 psi)
      High
      		1.37 to 1.57 MPa (14 to 16 kgf/cm2, 199 to 228 psi)



    2. Moisture is present in the air conditioning system.


      I022117E34


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      During operation, pressure on low pressure side cycles between normal and vacuum
      1. Moisture in air conditioning system freezes at the expansion valve orifice, causing refrigerant to temporarily stop circulating
      2. After the system stops, and warms up again, ice melts and normal operation is temporarily restored
      1. Cooler dryer (integrated into condenser tank) saturated with moisture
      2. Moisture in the air conditioning system freezes at expansion valve orifice and blocks circulation of refrigerant
      1. Replace cooler dryer
      2. Remove moisture by repeatedly evacuating air from the air conditioning system
      3. Recharge the air conditioning system with the proper amount of new or purified refrigerant



    3. Insufficient refrigerant


      I022118E17


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      1. Pressure is low on both low and high pressure sides
      2. Insufficient cooling performance
      		Refrigeration leaks from the system
      1. Insufficient refrigerant
      2. Refrigerant leaking
      1. Check for refrigerant leaks and repair if necessary
      2. Recharge the air conditioning system with the proper amount of new or purified refrigerant
      3. If the gauges indicate pressure of close to 0, then it is necessary to evacuate air conditioning system after repairing the leak



    4. Poor circulation of refrigerant


      I022119E18


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      1. Pressure is low on both low and high pressure sides
      2. Frost exists on pipe from condenser to evaporator unit
      		Refrigerant flow is obstructed by dirt inside the pipes of the condenser core
      		Condenser is clogged
      		Replace condenser



    5. Refrigerant does not circulate.


      I022120E17


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      1. Vacuum is indicated on low pressure side and very low pressure is indicated on high pressure side
      2. Frost or condensation is seen on piping on both sides of receiver/dryer or expansion valve
      1. Refrigerant flow is obstructed by moisture or dirt in air conditioning system
      2. Expansion valve is stuck closed
      		Refrigerant does not circulate
      1. Replace expansion valve
      2. Replace condenser
      3. Evacuate air conditioning system and supply the proper amount of new or purified refrigerant



    6. Air conditioning system is overcharged or cooling effectiveness of condenser is insufficient.


      I022121E18


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      Pressure is too high on both low and high pressure sides
      1. Unable to develop sufficient performance due to excessive amount of refrigerant
      2. Cooling effectiveness of condenser is insufficient
      1. Excessive amount of refrigerant in air conditioning system → excessive refrigerant was added during recharging
      2. Condenser cooling effectiveness is insufficient → condenser fins are clogged or cooling fan is faulty
      1. Clean condenser
      2. Check the operation of condenser cooling fan
      3. If 1 and 2 are normal, check the amount of refrigerant and recharge the air conditioning system with the proper amount of new or purified refrigerant



    7. Air is present in the air conditioning system.


      I022122E19


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      1. Pressure is too high on both low and high pressure sides
      2. The low pressure piping is too hot to touch
      		Air in air conditioning system
      1. Air present in air conditioning system
      2. Insufficient vacuum purging when evacuating the air conditioning system
      1. Replace cooler drier
      2. Check compressor oil to see if it is dirty or insufficient
      3. Evacuate the air conditioning system and recharge it with new or purified refrigerant



    8. Expansion valve malfunction


      I022123E15


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      1. Pressure is too high on both low and high pressure sides
      2. Frost or a large amount of condensation on piping on low pressure side
      		Expansion valve may be stuck open or metering refrigerant incorrectly
      1. Excessive refrigerant in low pressure piping
      2. Expansion valve open too wide
      		Replace expansion valve



    9. Insufficient compressor compression


      I022124E13


      Symptom
      		Probable Cause
      		Diagnosis
      		Corrective Actions
      1. Pressure is too high on both low and high pressure sides
      2. Pressure is too low on high pressure side
      		Internal leak in compressor
      1. Low compression
      2. Leak from a damaged valve or other compressor component
      		Replace compressor
      Gauge readings (Reference)


      I030081E43