Toyota Corolla (E120): On–vehicle inspection

1. Inspect refrigerant pressure with manifold gauge set

  1.  this is a method in witch the trouble is located by using a manifold gauge set. Read the manifold gauge pressure when the these conditions are established.

    Test conditions:

  • temperature at the air inlet with the switch set at recirc is 30 – 35 °c (86 – 95 °f)
  • engine running at 1500 rpm
  • blower speed control switch at ”hi” position
  • temperature control dial at ”cool” position a/c switch on
  • fully open doors

  1. Normally functioning refrigeration system.

    Gauge reading:
    low pressure side:
    0.15 – 0.25 Mpa (1.5 – 2.5 Kgf/cm2) high pressure side:
    1.37 – 1.57 Mpa (14 – 16 kgf/cm2)

  1. Moisture present in refrigeration system.

Symptom

Probable cause

Diagnosis

Remedy

During operation, pressure on low pressure side sometimes become a vacuum and sometime normal Moisture in refrigerating system freezes at expansion valve orifice causing a temporary stop of cycle, however, when it melts, normal state is restored.
  • Drier in oversaturected state
  • moisture in refrigerating 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 proper amount of new refrigerant
  1. Insufficient cooling

Symptom

Probable cause

Diagnosis

Corrective actions

  • Pressure low on both low and high pressure sides
  • insufficient cooling performance
Gas leakage in refrigeration system
  • Insufficient refrigerant
  • refrigerant leaking
  1. Check for gas leakage and repair if necessary
  2.  supply proper amount of new refrigerant
  3.  if indicated pressure value is close to a 0 when connected to gauge, create the vacuum after inspecting and repairing location of leak
  1. Poor circulation of refrigerant

Symptom

Probable cause

Diagnosis

Corrective actions

  • Pressure low on both low and high pressure sides
  • frost on pipe from condenser to unit
Refrigerant flow obstructed by dirt in receiver Receiver clogged Replace condenser
  1. Refrigerant does not circulate

Symptom

Probable cause

Diagnosis

Corrective actions

  • Vacuum indicated on low pressure side, very low pressure indicated on high pressure side
  • frost or dew seen on piping before and after receiver/ drier or expansion valve
  • Refrigerant flow obstructed by moisture or dirt in refrigerating system
  • refrigerant flow obstructed by gas leaked from expansion valve
Refrigerant does not circulate
  1. Check expansion valve
  2.  clean out dirt in expansion valve by air blowing
  3.  replace condenser
  4.  evaporate air and supply proper amount of new refrigerant.
  5.  For gas leakage from expansion valve, replace expansion valve
  1. Refrigerant overcharged or insufficient cooling of condenser

Symptom

Probable cause

Diagnosis

Corrective actions

  • Pressure too high on both low and high pressure sides
  • Unable to develop sufficient performance due to excessive use of refrigerating system
  • insufficient cooling of condenser
  • Excessive refrigerant in cycle"too much refrigerant supplied
  • condenser cooling insufficient"condenser fins clogged at cooling fan
  1. Clean condenser
  2.  check cooling fan with cooling fan motor operation
  3.  if (1) and (2) are in normal state, check amount of refrigerant and supply proper amount of refrigerant
  1. Air present in refrigeration system

Symptom

Probable cause

Diagnosis

Corrective actions

  • Pressure too high on both low and high pressure sides
  • the low pressure piping too hot to the touch
Air entered in refrigerating system
  • Air present in refrigerating system
  • insufficient vacuum purging
  1. Check compressor oil to see if it is see if it is dirty or insufficient
  2.  evacuate air and supply new refrigerant
  1. Expansion valve improperly

Symptom

Probable cause

Diagnosis

Corrective actions

  • Pressure too high on both low and high pressure sides
  • frost or large amount of dew on piping on low pressure side
Trouble in expansion valve
  • Excessive refrigerant in low pressure piping
  • expansion valve opened too wide
Check expansion valve
  1. Defective compression compressor

Symptom

Probable cause

Diagnosis

Corrective actions

  • Pressure too high on low high pressure sides
  • pressure too low to on high pressure side
Internal leak in compressor
  • Compression failure
  • leakage from valve damaged or broken sliding parts
Repair or replace compressor

Gauge readings (reference)

Replacement

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