Toyota Tacoma manuals

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

ON-VEHICLE INSPECTION

PROCEDURE

1. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

(a) This is a method to specify trouble areas by using a manifold gauge set. Read the manifold gauge pressure when the following conditions are established.

Test conditions:

  • Engine has been warmed up.
  • All doors are fully open.
  • A/C switch is ON.
  • Engine is running at 1,500 rpm.
  • Air inlet mode selector damper is set at recirculation.
  • Temperature control switch is in MAX. COLD position.
  • Blower speed control switch is in HI position.
  • Air temperature at the air inlet is 30 to 35°C (86 to 95°F).

Gauge readings (Reference)

(1) When the refrigerant volume is proper:

Gauge reading:

Low pressure side:

150 to 250 kPa (1.5 to 2.5 kgf/cm2, 22 to 36 psi)

High pressure side:

1370 to 1570 kPa (14.0 to 16.0 kgf/cm2, 199 to 228 psi)

(2) When there is moisture in the refrigeration system:

Symptoms

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 temporary stop of cycle. However, when melted, normal state restored

  • Drier 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) When cooling is insufficient:

Symptoms

Probable Cause

Diagnosis

Corrective Actions

  • 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 when connected to gauge, create vacuum after inspecting and repairing the location of leakage

(4) When the circulation of the refrigerant is poor:

Symptoms

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) When the refrigerant does not circulate:

Symptoms

Probable Causes

Diagnosis

Corrective Actions

  • 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
  2. Clean expansion valve by blowing air
  3. Replace condenser
  4. Evacuate air and charge appropriate volume of new refrigerant
  5. For gas leakage from expansion valve, replace expansion valve

(6) When the refrigerant is overcharged or cooling of condenser is insufficient:

Symptoms

Probable Causes

Diagnosis

Corrective Actions

Pressure extremely high on both low and high pressure sides

  • Excessive refrigerant
  • Cooling performance of condenser insufficient
  • Excessive refrigerant
  • Cooling performance of condenser insufficient
  1. Clean condenser
  2. Check condenser fan motor operation
  3. If 1 and 2 normal, check the amount of refrigerant and supply appropriate volume of refrigerant

(7) When there is air in the refrigeration system:

Symptoms

Probable Cause

Diagnosis

Corrective Actions

  • Pressure extremely high on both low and high pressure sides
  • The low pressure piping too hot to touch

Air in refrigeration system

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

(8) When the expansion valve malfunctions:

Symptoms

Probable Cause

Diagnosis

Corrective Action

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

Trouble in expansion valve

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

Replace expansion valve

(9) When the compressor is defective:

Symptoms

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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