Toyota Highlander manuals

Toyota Highlander Service Manual: On-vehicle inspection

1. INSPECT REFRIGERANT VOLUME

 

(a) Check the sight glass on the cooler refrigerant liquid pipe A.

Test conditions:

Item

Symptom

Amount of refrigerant

Corrective Actions

1

Bubbles exist Insufficient* (1) Check for gas leakage and repair if necessary (2) Add refrigerant until bubbles disappear
2 No bubbles exist Empty, insufficient or excessive Refer to 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 Considerable temperature difference between compressor inlet and outlet Proper or excessive Refer to 5 and 6
5 Immediately after air conditioning is turned off, refrigerant clears Excessive (1) Discharge refrigerant (2) Remove air and supply proper amount of purified refrigerant
6 Immediately after air conditioning is turned off, refrigerant foams and then becomes clear Proper

-

*: 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

(a) This is a method in which the trouble is located by using a manifold gauge set. Read the manifold gauge pressure when these conditions are established.

Test conditions:

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


  1.  Normally functioning refrigeration system

Gauge reading: Low pressure side: 0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2) High pressure side: 1.37 to 1.57 MPa (14 to 16 kgf/cm2)

  1. Moisture is present in refrigeration system

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

During operation, pressure on low pressure side cycles between normal and vacuum Moisture in refrigeration system freezes at expansion valve orifice, causing a temporary stop of cycle.

However, when it melts, normal state is restored.

  • Drier in oversaturated state
  • Moisture in refrigeration 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

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

  • Pressure is low on both low and high pressure sides
  • Bubbles are seen through sight glass continuously
  • 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 the indicated pressure value is close to 0 when connected to the gauge, create a vacuum after inspecting and repairing the location of leakage.
  1. Poor circulation of refrigerant

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Action

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

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

  • Vacuum is indicated on low pressure side and very low pressure is indicated on high pressure side
  • Frost or dew is seen on piping on both sides of receiver/drier or expansion valve
  • Refrigerant flow is obstructed by moisture or dirt in refrigeration system
  • Refrigerant flow is obstructed by a gas leak from expansion valve
Refrigerant does not circulate
  1. Check the expansion valve
  2.  Clean out dirt in expansion valve by blowing air
  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 is overcharged or cooling effectiveness of condenser is insufficient

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

  • Pressure is too high on both low and high pressure sides
  • No air bubbles are seen through sight glass even when engine rpm lowers
  • Unable to develop sufficient performance due to excessive use of refrigeration system
  • Cooling effectiveness of condenser is insufficient
  • Excessive refrigerant in cycle "excessive refrigerant is supplied
  • Condenser cooling effectiveness is insufficient "condenser fins are clogged at cooling fan
  1. Clean condenser
  2.  Check cooling fan with cooling fan motor operation
  3.  If (1) and (2) are normal check the amount of refrigerant and supply proper amount of refrigerant
  1. Air present in refrigeration system

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

  • Pressure is too high on both low and high pressure sides
  • The low pressure piping is too hot to touch
  • Bubbles can be seen through sight glass
Air in 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 supply new refrigerant
  1. Expansion valve malfunction

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

  • Pressure is 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 compressor

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Symptom

Probable cause

Diagnosis

Corrective Actions

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

Gauge readings (Reference)

INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET


Refrigerant
...

Replacement
1. DISCHARGE REFRIGERANT FROM REFRIGERATION SYSTEM (a) Turn the A/C switch on. (b) Operate the cooler compressor at an engine rpm of approximately 1,000 for 5 to 6 minutes to circulate the refrig ...

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