Toyota Corolla Quiz
Heater & air conditioner

On–vehicle inspection

In this manual: Heater & air conditioner
Introduction — 31Preparation — 32Service specifications — 19Diagnostics — 497Engine control system — 6Fuel — 13Emission control — 28Exhaust — 3Cooling — 13Lubrication — 7Ignition — 3Starting & charging — 13Front suspension — 12Rear suspension — 9Tire & wheel — 1Drive shaft / propeller shaft — 15Brake — 42Automatic transmission / trans — 47Clutch — 19Steering column — 9Power steering — 11Heater & air conditioner — 20Supplemental restraint system — 27Seat belt — 12Lighting — 18Wiper & washer — 9Audio & visual — 12Wiring — 1Communication system — 1Windshield/windowglass/mirror — 31Seat — 10Theft deterrent & door lock — 10Sliding roof/convertible — 8Engine hood/door — 12Exterior/interior trim — 20Vehicle control system — 1Cruise control — 5Maintenance — 8
18steps
~108min
4/5difficulty
Done 0 of 18
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
Toyota Corolla. Inspect refrigerant pressure with manifold gauge set
  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)

  2. Moisture present in refrigeration system.
    Toyota Corolla. Inspect refrigerant pressure with manifold gauge set
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
Toyota Corolla. 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
Toyota Corolla. 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
Toyota Corolla. 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
Toyota Corolla. 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
Toyota Corolla. 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
Toyota Corolla. 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
Toyota Corolla. 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)
Toyota Corolla. Gauge readings

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