REFRIGERANT(for HFO-1234yf(R1234yf)) ON-VEHICLE INSPECTION

PROCEDURE


  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 power switch is on (READY).

      • 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. A003P5NC01
        *a LO
        *b HI

        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

        1420 to 1620 kPa (14.5 to 16.5 kgf/cm2, 206 to 235 psi)

      2. Abnormally functioning air conditioning system


        1. A003OFJC01
          *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 Accumulator and accessory assembly saturated with moisture
          Moisture in air conditioning system is freezing at expansion valve orifice and blocking circulation of refrigerant
          Corrective Actions Replace accumulator and accessory assembly
          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. A003OXNC01
          *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 leaks

          Tech Tips

          For the example above, there is insufficient refrigerant.

        3. A003L3MC10
          *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 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 example above, there is an expansion valve malfunction.

        4. A003MIPC09
          *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 damaged valve or other compressor component
          Corrective Actions Replace compressor

          Tech Tips

          For the example above, there is insufficient compressor compression.

      3. Gauge readings (Reference)

        A003MO7C01
        *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