Last Modified: 04-05-2023 6.11:8.1.0 Doc ID: RM100000000VK1U
Model Year Start: 2016 Model: Sienna Prod Date Range: [12/2015 -           ]
Title: HEATING / AIR CONDITIONING: REFRIGERANT: ON-VEHICLE INSPECTION; 2016 - 2020 MY Sienna [12/2015 -        ]

ON-VEHICLE INSPECTION

PROCEDURE

1. CHECK REFRIGERANT PRESSURE USING MANIFOLD GAUGE SET

(a) This is a method to identify trouble areas by using a manifold gauge set. Read the manifold gauge pressure under the following conditions.

Test conditions:

  • Engine warm.
  • All doors fully open.
  • A/C switch is on.
  • Blower speed control switch at HI.
  • Engine running at 1500 rpm.
  • Air inlet mode damper set at RECIRC.
  • Temperature control switch in MAX. COLD position.
  • Air temperature at air inlet 30 to 35°C (86 to 95°F).

(1) When the refrigerant volume is correct, the gauge reading indicates as follows:

Gauge Reading:

Pressure Side

Specified Condition

Low

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

High

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

HINT:

Pressure varies in accordance with certain conditions (outside air temperature, sunlight and wind).

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

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 interruption of cycle

However, when melted, returns to normal condition
  • Receiver dryer oversaturated
  • Moisture in refrigeration system freezes at expansion valve orifice and blocks refrigerant circulation
  1. Replace receiver dryer
  2. Remove moisture from cycle by repeatedly evacuating air
  3. Charge appropriate volume of new refrigerant

(3) When cooling is insufficient:

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 using halogen leak detector, and repair if necessary
  2. Charge appropriate volume of new refrigerant
  3. If indicated pressure value close to 0 when connected to gauge, create vacuum after inspecting and repairing location of leakage

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

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) When the refrigerant does not circulate:

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
  2. Clean expansion valve with compressed air
  3. Replace condenser
  4. Evacuate air and then 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:

Symptom

Probable Cause

Diagnosis

Corrective Action
  • Pressure extremely high on both sides
  • Excessive refrigerant
  • Cooling performance of condenser insufficient
  • Excessive refrigerant
  • Cooling performance of condenser insufficient
  1. Clean condenser fins
  2. Check condenser fan motor operation by switching A/C ON
  3. If 1 and 2 normal, check amount of refrigerant and charge appropriate volume of refrigerant

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

Symptom

Probable Cause

Diagnosis

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

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

(8) When the expansion valve malfunctions:

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

Expansion valve malfunction
  • Excessive refrigerant in low pressure piping
  • Expansion valve opening too wide

Replace expansion valve

(9) When the compressor is defective:

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 of compressor
  • Leakage from damaged valve or broken sliding parts in compressor

Repair or replace compressor

2. INSPECT IDLING SPEED

(a) Warm up the engine.

(b) Inspect idling speed when these conditions are established.

  • Check the idle speed with the cooling fans off.
  • Turn off all the electrical systems.
  • When checking the idle speed, the transaxle should be in neutral or park.

Standard:

Condition

Idling Speed

A/C switch is off

600 to 700 rpm

A/C switch is on (A/C Lo → Hi)

650 → 800 rpm

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