Toyota Tacoma manuals

Toyota Tacoma 2015-2018 Service Manual: On-vehicle Inspection

ON-VEHICLE INSPECTION

PROCEDURE

1. INSPECT REFRIGERANT PRESSURE

(a) This method uses a refrigerant recovery unit set to locate problem areas. Read the refrigerant pressure when the test conditions are established.

Test conditions:

  • Temperature at the air inlet with the air recirculation switch set at RECIRC is 30 to 35°C (86 to 95°F).
  • Engine is running at 1500 rpm.
  • All doors are fully open.
  • Blower speed control switch is set to HI.
  • A/C switch is on.

Gauge readings (Reference):

Text in Illustration

*a

Pressure on low-pressure side

*b

Blower HI Zone

*c

Blower LO Zone

*d

Pressure on high-pressure side

(1) Normally functioning refrigeration system.

Gauge Reading:

Pressure Side

Refrigerant Volume

Low

0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2)

High

1.37 to 1.57 MPa (14 to 16 kgf/cm2)

(2) The A/C system periodically changes between normal and improper function due to moisture in the refrigerant system.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

During operation, pressure on low pressure side cycles between normal and vacuum

Moisture in refrigeration system freezes at expansion valve orifice, causing temporary stop of cycle. However, when melted, normal state is restored.

  • Dryer is overly saturated
  • Moisture in refrigeration system freezes at expansion valve orifice and blocks refrigerant circulation
  1. Remove moisture from cycle by repeatedly evacuating air
  2. Supply appropriate volume of new refrigerant

(3) The A/C system does not function effectively due to insufficient refrigerant.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

  • Pressure low on both low and high pressure sides
  • Cooling performance insufficient

Gas leakage from refrigeration system

  • Insufficient refrigerant
  • Refrigerant leakage
  1. Check for gas leakage and repair if necessary
  2. Supply appropriate volume of new refrigerant
  3. If indicated pressure value close to 0 with gauge connected, create vacuum after inspecting and repairing location of leakage

(4) The A/C system does not function effectively due to poor circulation of the refrigerant.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

  • Pressure low on both low and high pressure sides
  • Frost exists on piping from condenser to A/C unit

Refrigerant flow obstructed by dirt in condenser

Condenser clogged

Replace condenser

(5) The A/C system does not function or functions intermittently because the refrigerant does not circulate.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

  • Vacuum indicated on low pressure side, and extremely low pressure indicated on high pressure side
  • Frost or condensation seen on piping on both sides of condenser 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 refrigerant
  2. Clean expansion valve using compressed air
  3. Replace condenser
  4. Evacuate air and charge system with appropriate volume of new refrigerant
  5. For gas leakage from expansion valve, replace expansion valve

(6) The A/C system does not function effectively due to the system being overcharged with refrigerant or insufficient cooling of the condenser.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

Pressure extremely high on both low and high-pressure sides

  • Excessive refrigerant
  • Cooling performance of condenser insufficient
  • Condenser is dirty
  • Condenser fan motor is malfunctioning
  • Excessive refrigerant
  1. Clean condenser
  2. Check condenser fan motor operation
  3. If actions taken in 1 and 2 do not solve problem, check amount of refrigerant and adjust amount of refrigerant to appropriate amount

(7) The A/C system does not function due to air in the refrigeration system.

CAUTION:

The low-pressure piping may be very hot and cause serious burns.

NOTICE:

These gauge indications occur when the refrigeration system opens and the system is charged with refrigerant without vacuum purging.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

  • Pressure extremely high on both low and high-pressure sides
  • Low-pressure piping is too hot to touch

Air in refrigeration system

  • Air in refrigeration system
  • Vacuum purging insufficient
  1. Check if compressor oil is dirty or insufficient
  2. Evacuate air and charge system with new refrigerant

(8) The A/C system does not function effectively due to an expansion valve malfunction.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

  • Pressure extremely high on both low and high-pressure sides
  • Frost or condensation on piping on low-pressure side

Problem with expansion valve

  • Excessive refrigerant in low pressure piping
  • Expansion valve open too widely

Replace expansion valve

(9) The A/C system does not function due to a defective compressor.

Text in Illustration

*a

Low Pressure Side

*b

High Pressure Side

Symptom

Probable Cause

Diagnosis

Corrective Action

  • Pressure extremely high on both low and high-pressure sides
  • Pressure extremely low on high pressure side

Internal leakage in compressor

  • Compression failure
  • Leakage from damaged valve or broken sliding parts

Repair or replace compressor

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...

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