Last Modified: 08-21-2023 6.11:8.1.0 Doc ID: RM100000001AY7Q
Model Year Start: 2019 Model: Avalon HV Prod Date Range: [04/2018 -           ]
Title: HEATING / AIR CONDITIONING: REFRIGERANT: ON-VEHICLE INSPECTION; 2019 - 2022 MY Avalon Avalon HV [04/2018 -        ]

ON-VEHICLE INSPECTION

PROCEDURE

1. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

HINT:

The following examples show the readings of a manifold gauge set and the corresponding air conditioning system problems.

(a) Read the manifold gauge pressure when the following conditions are met:

  • The doors are fully open.
  • The engine is idling (for Gasoline Model) or power switch is on (READY) (for HV Model).
  • The A/C switch is on.
  • The temperature is set to max cold.
  • The blower speed is set to high.
  • The temperature at the air inlet with recirculate selected is 30 to 35°C (86 to 95°F).

(1) Normal functioning air conditioning system

Gauge Reading

Pressure Side

Refrigerant Volume

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)

*a

LO

*b

HI

(2) Abnormally functioning air conditioning system

*a

LO

*b

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

    Symptom

    Air conditioning system periodically cools and then fails to cool

    Probable Cause

    Moisture in air conditioning system freezes at expansion valve orifice, causing refrigerant to temporarily stop circulating

    After system stops and warms up again, ice melts and normal operation is temporarily restored

    Diagnosis

    Cooler dryer (integrated into condenser tank) saturated with moisture

    Moisture in air conditioning system is freezing at expansion valve orifice and blocking circulation of refrigerant

    Corrective Actions

    Replace cooler dryer

    Remove moisture by repeatedly evacuating air from air conditioning system

    Recharge air conditioning system with proper amount of new or purified refrigerant

    HINT:

    For the example above, moisture is present in the air conditioning system.

  2. Pressure is low on both low and high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool effectively

    Insufficient cooling performance

    Probable Cause

    Refrigerant leaks from air conditioning system

    Diagnosis

    Insufficient refrigerant

    Refrigerant leaking

    Corrective Actions

    Check for refrigerant leaks and repair if necessary

    Recharge air conditioning system with proper amount of new or purified refrigerant

    If gauges indicate pressure of close to 0, then it is necessary to evacuate air conditioning system after repairing leaks

    HINT:

    For the example above, there is insufficient refrigerant.

  3. Pressure is low on both low and high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool effectively

    Frost exists on pipe from condenser to evaporator unit

    Probable Cause

    Refrigerant flow is obstructed by dirt inside pipes of condenser core

    Diagnosis

    Condenser is clogged

    Corrective Actions

    Replace condenser

    HINT:

    For the example above, there is poor circulation of refrigerant.

  4. Vacuum is indicated on low pressure side and very low pressure is indicated on high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool effectively (System may cool occasionally)

    Frost or condensation is seen on piping on both sides of receiver/dryer or expansion valve

    Probable Cause

    Refrigerant flow is obstructed by moisture or dirt in air conditioning system

    Expansion valve is stuck closed

    Diagnosis

    Refrigerant does not circulate

    Corrective Actions

    Replace expansion valve

    Replace condenser

    Evacuate air conditioning system and recharge with proper amount of new or purified refrigerant

    HINT:

    For the example above, the refrigerant does not circulate.

  5. Pressure is too high on both low and high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool effectively

    Probable Cause

    Unable to provide sufficient performance due to excessive amount of refrigerant

    Cooling effectiveness of condenser is insufficient

    Diagnosis

    Excessive amount of refrigerant in air conditioning system because excessive refrigerant was added during recharging

    Cooling effectiveness of condenser is insufficient because condenser fins are clogged or cooling fan is faulty

    Corrective Actions

    Clean condenser

    Check operation of condenser cooling fan

    If condenser is clean and fan operation is normal, check amount of refrigerant and recharge air conditioning system with proper amount of new or purified refrigerant

    HINT:

    For the example above, the air conditioning system is overcharged or cooling effectiveness of condenser is insufficient.

  6. Pressure is too high on both low and high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool

    The low pressure piping is too hot to touch

    Probable Cause

    Air in air conditioning system

    Diagnosis

    Air present in air conditioning system

    Insufficient vacuum purging when evacuating air conditioning system

    Corrective Actions

    Replace cooler dryer

    Check compressor oil to see if it is dirty or insufficient

    Evacuate air conditioning system and recharge it with new or purified refrigerant

    NOTICE:

    These gauge indications occur when the air conditioning system has been left open and then recharged without evacuating the system.

    HINT:

    For the example above, air is present in the air conditioning system.

  7. Pressure is too high on both low and high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool effectively

    Frost or large amount of condensation on piping on low pressure side

    Probable Cause

    Expansion valve may be stuck open or metering refrigerant incorrectly

    Diagnosis

    Excessive refrigerant in low pressure piping

    Expansion valve open too wide

    Corrective Actions

    Replace expansion valve

    HINT:

    For the example above, there is an expansion valve malfunction.

  8. Pressure is too high on both low and high pressure side or pressure is too low on high pressure side

    *a

    LO

    *b

    HI

    Symptom

    Air conditioning system does not cool effectively

    Probable Cause

    Internal leak in compressor

    Diagnosis

    Low compression

    Leak from damaged valve or other compressor component

    Corrective Actions

    Replace compressor

    HINT:

    For the example above, there is insufficient compressor compression.

(3) Gauge readings (Reference)

*a

Pressure on Low Pressure Side kPa (kgf/cm2, psi)

*b

Pressure on High Pressure Side kPa (kgf/cm2, psi)

*c

Blower High Zone

*d

Blower Low Zone