Refrigerant System Tests. General Procedures

Inspection

1. 1
   Drive the vehicle or let the engine run until it reaches normal operating temperature.
2. 2
   Set the air conditioning temperature to maximum cool with dual zone function off (if equipped). Manually set the blower fan to HI. If the vehicle has a fresh/recirculation air button, set it to recirculation. If the vehicle has an A/C switch or A/C compressor switch, set it to the OFF position.
3. 3
   Close all vehicle windows and doors.
4. 4
   Run the vehicle at idle for 5 minutes.
5. 5
   Make sure the cabin temperature is above 24 °C. Set the A/C or compressor switch to MAX A/C ON.
6. 6
   Run the vehicle at idle for 5 minutes.
7. 7
   Turn the engine OFF and proceed to Procedure 2 — Ambient Temperature 21 °C to 38 °C.

Inspection

1. 1
   Run the engine until it reaches normal operating temperature.
2. 2
   Connect the A/C service manifold gauge set to the refrigerant system.
3. 3
   Set the A/C system temperature to the lowest possible setting with the dual-zone function turned off (if equipped). Manually set the blower to HI. If the vehicle has a fresh air/recirculation button, set it to FRESH. If the vehicle has an A/C switch or A/C compressor switch, set it to the A/C on position.
4. 4
   Open all vehicle windows and leave the hood open for inspection. Open the rear doors.
5. 5
   Make sure the compressor is running and the cooling fans are operating or engaged. Run the vehicle at idle until the suction (low-pressure side) and discharge (high-pressure side) pressures are stable or fluctuate within a repeating range.
6. 6
   Record the ambient (shop) temperature.
7. 7
   Record the discharge pressure. If the pressure fluctuates, record the average value.
8. 8
   Determine whether the discharge pressure is within normal operating range using the Normal Refrigerant Discharge Pressure 21–38 °C Ambient (30–60% relative humidity) chart below.

   

9. 9
   Record the suction pressure. If the pressure fluctuates, record the average value.
10. 10
    Determine whether the suction pressure is within the normal operating range using the Normal Refrigerant Suction Pressure 21–38 °C Ambient (30–60% relative humidity) chart below.

    

11. 11

    High (Discharge) Pressure	Low (Suction) Pressure	Component — Causes
    High	Normal to High	Condenser – insufficient airflow Engine – overheating
    Normal to High	Normal	Overcharged refrigerant – air in the refrigerant
    Normal to Low	High	A/C compressor – low performance
    Normal to Low	Normal to High	A/C suction line partially blocked or restricted.
    Normal to Low	Low	Low refrigerant charge — leak in the system. A/C suction line partially blocked or restricted b
    Erratic operation or compressor does not operate		Ambient air temperature (AAT) sensor - poor connection A/C pressure sensor – poor connection Evaporator temperature sensor – poor connection Low refrigerant charge – leak in the system
    Additional possible components or causes related to improper compressor operation
    Compressor drive belt — loose. Compressor clutch — slipping. Clutch coil open — short circuit or loose mounting. Control module switch — dirty contacts or stuck open. Clutch wiring circuit — high resistance, open circuit, or blown fuse. Compressor operation interrupted by engine computer.
    Additional possible components or causes related to a damaged compressor
    Incorrect clutch air gap. Suction accumulator — oil bleed hole clogged. Refrigerant leaks.

    
    

    a Low-pressure reading will be normal or high if the restriction is located downstream of the service access valve.

    b Low-pressure reading will be low if the restriction is located upstream of the service access valve.

Inspection

1. 1
   Run the engine until it reaches normal operating temperature.
2. 2
   Connect the A/C service manifold gauge set to the refrigerant system.
3. 3
   Set the A/C system temperature to the lowest possible setting with the dual-zone function turned off (if equipped). Manually set the blower to HI. If the vehicle has a fresh air/recirculation button, set it to FRESH. If the vehicle has an A/C switch or A/C compressor switch, set it to the A/C on position.
4. 4
   Open all vehicle windows and leave the hood open for testing. Open the rear hatch and/or rear doors (if equipped).
5. 5
   Make sure the compressor is running and the cooling fans are operating or engaged. Run the vehicle at idle until the suction (low-pressure side) and discharge (high-pressure side) pressures are stable or fluctuate within a repeating range.
6. 6
   Record the ambient (shop) temperature.
7. 7
   Record the discharge pressure. If the pressure fluctuates, record the average value.
8. 8
   Determine whether the discharge pressure is within normal operating limits using the Normal Refrigerant Discharge Pressure 38–49 °C Ambient (15–40% relative humidity) chart below.

   

9. 9
   Record the suction pressure. If the pressure fluctuates, record the average value.
10. 10
    Determine whether the suction pressure is within normal operating limits using the Normal Refrigerant Suction Pressure 38–49 °C Ambient (15–40% relative humidity) chart below.

    

11. 11

    High (Discharge) Pressure	Low (Suction) Pressure	Component — Causes
    High	Normal to High	Condenser – insufficient airflow Engine – overheating
    Normal to High	Normal	Overcharged refrigerant – air in the refrigerant
    Normal to Low	High	A/C compressor – low performance
    Normal to Low	Normal to High	A/C suction line partially blocked or restricted.
    Normal to Low	Low	Low refrigerant charge — leak in the system. A/C suction line partially blocked or restricted b
    Erratic operation or compressor does not operate		Ambient air temperature (AAT) sensor - poor connection A/C pressure sensor – poor connection Evaporator temperature sensor – poor connection Low refrigerant charge – leak in the system
    Additional possible components or causes related to improper compressor operation
    Compressor drive belt — loose. Compressor clutch — slipping. Clutch coil open — short circuit or loose mounting. Control module switch — dirty contacts or stuck open. Clutch wiring circuit — high resistance, open circuit, or blown fuse. Compressor operation interrupted by engine computer.
    Additional possible components or causes related to a damaged compressor
    Incorrect clutch air gap. Suction accumulator — oil bleed hole clogged. Refrigerant leaks.

    
    

    a Low-pressure reading will be normal or high if the restriction is located downstream of the service access valve.

    b Low-pressure reading will be low if the restriction is located upstream of the service access valve.