REFRIGERANT (for TMMK Made) ON-VEHICLE INSPECTION


  1. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

    Tech Tips

    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:


      • Doors are fully open.

      • The engine is idling.

      • The A/C switch is on.

      • The temperature is set to max cool.

      • The blower speed is set to high.

      • Temperature at the air inlet with recirculate selected is 30 to 35°C (86 to 95°F).


      1. B000K5B

        Normally functioning air conditioning system.

        Gauge Reading
        Pressure Side Refrigerant Volume
        Low

        150 to 250 kPa (1.5 to 2.5 kgf/cm2, 22 to 36 psi)
        High

        1370 to 1570 kPa (14.0 to 16.0 kgf/cm2, 199 to 228 psi)

      2. Abnormally functioning air conditioning system.


        1. B000LMYE01
          Text in Illustration
          *a LO
          *b HI

          During operation, pressure on low pressure side cycles between normal and vacuum

          Symptom Air conditioning system periodically cools and then fails to cool.
          Probable Cause Moisture in air conditioning system freezes at expansion valve orifice, causing refrigerant to temporarily stop circulating
          After system stops, and warms up again, ice melts and normal operation is temporarily restored
          Diagnosis Cooler dryer (integrated into condenser tank) saturated with moisture
          Moisture in air conditioning system freezes at expansion valve orifice and blocks circulation of refrigerant
          Corrective Actions Replace cooler dryer
          Remove moisture by repeatedly evacuating air from air conditioning system
          Recharge air conditioning system with proper amount of new or purified refrigerant

          Tech Tips

          For the example above, moisture is present in the air conditioning system.

        2. B000HTEE01
          Text in Illustration
          *a LO
          *b HI

          Pressure is low on both low and high pressure sides

          Symptom Air conditioning system does not cool effectively.
          Insufficient cooling performance
          Probable Cause Refrigerant leaks from air conditioning system
          Diagnosis Insufficient refrigerant
          Refrigerant leaking
          Corrective Actions Check for refrigerant leaks and repair if necessary
          Recharge air conditioning system with proper amount of new or purified refrigerant
          If gauges indicate pressure of close to 0, then it is necessary to evacuate air conditioning system after repairing leak

          Tech Tips

          For the example above, there is insufficient refrigerant.

        3. B000KG7E01
          Text in Illustration
          *a LO
          *b HI

          Pressure is low on both low and high pressure sides

          Symptom Air conditioning system does not cool effectively.
          Frost exists on pipe from condenser to evaporator unit
          Probable Cause Refrigerant flow is obstructed by dirt inside pipes of condenser core
          Diagnosis Condenser is clogged
          Corrective Actions Replace condenser

          Tech Tips

          For the example above, there is poor circulation of refrigerant

        4. B000N10E01
          Text in Illustration
          *a LO
          *b HI

          Vacuum is indicated on low pressure side and very low pressure is indicated on high pressure side

          Symptom Air conditioning system does not cool effectively. (System may cool occasionally)
          Frost or condensation is seen on piping on both sides of receiver/dryer or expansion valve
          Probable Cause Refrigerant flow is obstructed by moisture or dirt in air conditioning system
          Expansion valve is stuck closed
          Diagnosis Refrigerant does not circulate
          Corrective Actions Replace expansion valve
          Replace condenser
          Evacuate air conditioning system and supply proper amount of new or purified refrigerant

          Tech Tips

          For the example above, the refrigerant does not circulate.

        5. B000HD9E01
          Text in Illustration
          *a LO
          *b HI

          Pressure is too high on both low and high pressure sides

          Symptom Air conditioning system does not cool effectively.
          Probable Cause Unable to develop sufficient performance due to excessive amount of refrigerant
          Cooling effectiveness of condenser is insufficient
          Diagnosis Excessive amount of refrigerant in air conditioning system → excessive refrigerant was added during recharging
          Cooling effectiveness of condenser is insufficient → condenser fins are clogged or cooling fan is faulty
          Corrective Actions Clean condenser
          Check operation of condenser cooling fan
          If above two corrective actions are normal, check amount of refrigerant and recharge air conditioning system with proper amount of new or purified refrigerant

          Tech Tips

          For the example above, the air conditioning system is overcharged or cooling effectiveness of condenser is insufficient.

        6. B000MB7E01
          Text in Illustration
          *a LO
          *b HI

          Pressure is too high on both low and high pressure sides

          Symptom Air conditioning system does not cool.
          The low pressure piping is too hot to touch
          Probable Cause Air in air conditioning system
          Diagnosis Air present in air conditioning system
          Insufficient vacuum purging when evacuating air conditioning system
          Corrective Actions Replace cooler drier
          Check compressor oil to see if it is dirty or insufficient
          Evacuate air conditioning system and recharge it with new or purified refrigerant

          Note

          These gauge indications occur when the air conditioning system has been left open and then recharged without evacuating the system.

          Tech Tips

          For the example above, air is present in the air conditioning system.

        7. B000MESE01
          Text in Illustration
          *a LO
          *b HI

          Pressure is too high on both low and high pressure sides

          Symptom Air conditioning system does not cool effectively.
          Frost or a large amount of condensation on piping on low pressure side
          Probable Cause Expansion valve may be stuck open or metering refrigerant incorrectly
          Diagnosis Excessive refrigerant in low pressure piping
          Expansion valve open too wide
          Corrective Actions Replace expansion valve

          Tech Tips

          For the above example, there is an expansion valve malfunction.

        8. B000MTCE01
          Text in Illustration
          *a LO
          *b HI

          Pressure is too high on both low and high pressure sides or pressure is too low on high pressure side

          Symptom Air conditioning system does not cool effectively.
          Probable Cause Internal leak in compressor
          Diagnosis Low compression
          Leak from a damaged valve or other compressor component
          Corrective Actions Replace compressor

          Tech Tips

          For the above example, there is insufficient compressor compression.

      3. Gauge readings (Reference)

        B000MKJE04
        Text in Illustration
        *a

        Pressure on low pressure side kPa (kgf/cm2, psi)

        		 *b

        Pressure on high pressure side kPa (kgf/cm2, psi)
        *c Blower high zone *d Blower low zone