Toyota
Toyota Land Cruiser
 Service Manual
Air conditioning Air conditioning system
On-vehicle inspection

1. INSPECT REFRIGERANT VOLUME

 

Observe the sight glass on the liquid tube.

Test conditions:

  • Engine speed at 1,500 rpm
  • Fan speed selector at "HI" position
  • A/C switch ON
  • Temperature control dial at "COOL" position
  • Doors fully opened

Item

Symptom

Amount of refrigerant

Remedy

1 Bubbles appear in sight glass Insufficient* (1) Check for gas leakage with gas leak detector and repair, if necessary (2) Add refrigerant until bubbles disappear
2 No bubbles appear in sight glass None, sufficient or too much Refer to item 3 and 4
3 No temperature difference between compressor inlet and outlet Empty or nearly empty (1) Check for gas leakage with gas leak detector and repair, if necessary (2) Add refrigerant until bubbles disappear
4 Temperature between compressor inlet and outlet is noticeably different Correct or too much Refer to items 5 and 6
5 Immediately after air conditioning system is turned off, refrigerant in sight glass stays clear Too much (1) Discharge refrigerant (2) Evacuate air and charge proper amount of purified refrigerant
6 When air conditioning system is turned off, refrigerant foams and then stays clear Correct  

*: Bubbles in the sight glass with ambient temperatures higher than usual can be considered normal if cooling is sufficient.

2. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

Check the trouble area using a set of manifold gauge set. Read the manifold gauge pressure when following conditions are detected.

Test conditions:

  • Temperature at the air inlet with the switch set
  • at RECIRC is 30 - 35 C (86 - 95 F)
  • Engine running at 2,000 rpm
  • Fan speed selector at "HI" position
  • Temperature control dial on "COOL" position

HINT: It should be noted that the gauge indications may vary depending on ambient temperature conditions.

  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 - 15 kgf/cm2)

  1. Moisture present in refrigeration system.

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

During operation, pressure on low pressure side sometimes become a vacuum and sometime normal Moisture entered in refrigeration system freezes at expansion valve orifice and temporarily stops cycle, but normal state is restored after a time when the ice melts
  • Drier in over-saturated state
  • Moisture in refrigeration system freezes at expansion valve orifice and blocks circulation of refrigerant
  1. Replace condenser
  2.  Remove moisture in cycle through repeatedly evacuating air
  3.  Charge proper amount of new refrigerant
  1. Insufficient cooling

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

  • Pressure low on both low and high pressure sides
  • Bubbles seen in sight glass continuously
  • Insufficient cooling performance
Gas leakage at some place in refrigeration system
  • Insufficient refrigerant in system
  • Refrigerant leaking
  1. Check for gas leakage with gas leak detector and repair if necessary
  2. Charge proper amount of refrigerant
  3.  If indicated pressure value is near 0 when connected to gauge, create the vacuum after inspecting and repairing the location of the leak
  1. Poor circulation of refrigerant

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

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

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

  • Vacuum indicated on low pressure side, very low pressure indicated on high pressure side
  • Frost or dew seen on piping before and after condenser/ drier or expansion valve
  • Refrigerant flow obstructed by moisture or dirt in refrigeration system
  • Refrigerant flow obstructed by gas leakage from expansion valve
Refrigerant does not circulate
  1. Check expansion valve
  2.  Clean out dirt in expansion valve by blowing with air
  3.  Replace condenser
  4.  Evacuate air and charge new refrigerant to proper amount
  5.  For gas leakage from expansion valve, replace expansion valve
  1. Refrigerant overcharged or insufficient cooling of condenser.

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

  • Pressure too high on both low and high pressure sides
  • No air bubbles seen through the sight glass even when the engine rpm is lowered
  • Unable to develop sufficient performance due to excessive refrigeration system
  • Insufficient cooling of condenser
  • Excessive refrigerant in cycle " refrigerant over charged
  • Condenser cooling " condenser fins clogged or cooling fan faulty
  1. Clean condenser
  2.  Check cooling fan with fluid coupling operation
  3.  If (1) and (2) are in normal state, check amount of refrigerant, and charge proper amount of refrigerant
  1. Air present in refrigeration system

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

  • Pressure too high on both low and high pressure sides
  • The low pressure piping hot to touch
  • Bubbles seen in sight glass
Air entered in refrigeration system
  • Air present in refrigeration system
  • Insufficient vacuum purging
  1. Check compressor oil to see if it is dirty or insufficient
  2.  Evacuate air and charge new refrigerant
  1. Expansion valve improperly

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

  • 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, and replace if defective
  1. Defective compression compressor

Symptom seen in refrigeration system

Probable cause

Diagnosis

Remedy

  • Pressure too high on low and high pressure sides
  • Pressure too low on high pressure side
Internal leak in compressor
  • Compression defective
  • Valve leaking or broken sliding parts
Repair or replace compressor

3. INSPECT IDLE-UP SPEED

(a) Warm up engine (b) Inspect idle-up speed when following conditions are established.

Test conditions:

  • Fan speed selector at "HI" position
  • Temperature control dial at "COOL" position
  • A/C switch ON
  • Put gear shift in neutral

Magnetic clutch condition

Idle-up speed

Magnetic clutch not engaged 700 +- 50 rpm
Magnetic clutch engaged 780 +- 50 rpm

If idle speed is not as specified, check the idle control system.

4. INSPECT FOR LEAKAGE OF REFRIGERANT

(a) Stop engine.

(b) Secure good ventilation (The gas leak detector may not react to volatile gases which are not refrigerant, such as evaporated gasoline and exhaust gas) (c) Repeat the test 2 or 3 times (d) Make sure that there is some refrigerant remaining in the refrigeration system.

When compressor is OFF: approx. 392 - 588 kPa (4 - 6 kgf·cm2, 57 - 85 psi)

(e) Bring the gas leak detector close to the drain hose before performing the test.

HINT:

  • After the blower motor stops, leave the cooling for more than 15 minutes.
  • Expose the gas leak detector sensor under the drain hose.
  • When bring the gas leak detector close to the drain hose, make sure that the gas leak detector does not react to the volatile gases.

If gas leaks are detected, lift up the vehicle.

(f) If gas leaks are not detected on the drain hose, remove the blower resistor from the cooling unit. Then insert the gas leak detector sensor into the unit to perform the test.

(g) Disconnect the connector and leave the pressure switch for approx. 20 minutes. Then bring the gas leak detector close to the pressure switch to perform the test.

(h) Bring the gas leak detector close to the refrigerant lines.

    More about Air conditioning system:

    Charging

    Evacuating

    On-vehicle inspection

    Precaution

    Toyota Land Cruiser Service Manual / Air conditioning / Air conditioning system / On-vehicle inspection

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