Refrigerant System Tests

SPECIAL TOOL(S)

Courtesy of FORD MOTOR COMPANY	R-134A Side Wheel Manifold with Hoses 023-00047300-ROB40134AE
Courtesy of FORD MOTOR COMPANY	R134A REFRIGERANT RECOVERY RECYCLING And RECHARGE MA (R-134a Refrigerant Management Machine (SAE Compliant)) 300-ROB34288
Courtesy of FORD MOTOR COMPANY	A/C SERVICE MACHINE PRINTER 199-00067

Ambient Temperature at or Below 38°C (100°F)

NOTE: The system performance can be evaluated and diagnosed by analysis of the compressor suction and discharge pressures. The following procedure is used to determine if the system is operating at normal pressures.

NOTE: The procedure varies depending on the ambient (shop) temperature. If the ambient temperature is 38°C (100.3°F) or lower, follow Procedure 1. If the ambient temperature is over 38°C (100.3°F), follow Procedure 2.

NOTE: If the A/C compressor cycles at any time during this test, refer to the diagnostic table below.

1.

Drive the vehicle or run the engine until it reaches normal operating temperature.

2.

Connect a 023-00047 300-ROB40134AE, 199-00067 or 300-ROB34288 to the refrigerant system.

3.

Set the climate controls.
- If equipped with manual climate control, set the A/C controls for normal A/C -PANEL mode, full COOL temperature, FRESH air, HI blower. If the vehicle has a fresh air/recirc button, set it to FRESH. If the vehicle has an A/C switch or compressor on switch, set it to A/C ON.
- If equipped with EATC, set temperature to 15°C (59°F) (lowest possible temp setting) with the dual function disabled (if equipped). Manually set blower on HI. If the vehicle has a fresh air/recirc button, set it to FRESH. If the vehicle has an A/C switch or compressor on switch, set it to A/C ON.

4.

Open all vehicle windows and leave the hood open for the test. Open the rear doors.

5.

Confirm the compressor clutch is engaged and the engine cooling fan(s) are operating or engaged. Allow the vehicle to idle until the suction (low-side) and discharge (high-side) pressures are stable or fluctuate in a range that repeats.

6.

Record the ambient (shop) temperature.

7.

Record the discharge pressure. If the pressure is fluctuating, record the average value.

8.

Determine if the discharge pressure falls within the normal operating limits using the Normal Refrigerant Discharge Pressures chart.

Courtesy of FORD MOTOR COMPANY

9.

Record the suction pressure. If the pressure is fluctuating, record the average value.

10.

Determine if the suction pressure falls between normal operating limits using the Normal Refrigerant Suction Pressures chart in illustration.

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11.

Proceed to the Diagnostic Table below.

Ambient Temperature Above 38°C (100°F)

NOTE: If the A/C compressor cycles at any time during this test, refer to the diagnostic table below.

1.

Drive the vehicle or run the engine until it reaches normal operating temperature.

2.

Connect a 023-00047 300-ROB40134AE, 199-00067 or 300-ROB34288 to the refrigerant system.

3.

Set the climate controls.
- If equipped with manual climate control, set the A/C controls for normal A/C -PANEL mode, full COOL temperature, FRESH air, MED-LO blower. If the vehicle has a fresh air/recirc button, set it to FRESH. If the vehicle has an A/C switch or compressor on switch, set it to A/C ON.
- If equipped with EATC, set temperature to 15°C (59°F) (lowest possible temp setting). Manually set blower to MED-LO (3 to 4 bars). If the vehicle has a fresh air/recirc button, set it to FRESH. If the vehicle has an A/C switch or compressor on switch, set it to A/C ON.

4.

Open all vehicle windows and leave the hood open for the test. Open the rear hatch and/or rear doors (if equipped).

5.

Confirm the compressor clutch is engaged and the engine cooling fan(s) are operating or engaged. Allow the vehicle to idle until the suction (low-side) and discharge (high-side) pressures are stable or fluctuate in a range that repeats.

6.

Record the ambient (shop) temperature.

7.

Record the discharge pressure. If the pressure is fluctuating, record the average value.

8.

Determine if the discharge pressure falls within the normal operating limits using the Normal Refrigerant Discharge Pressures chart in illustration.

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9.

Record the suction pressure. If the pressure is fluctuating, record the average value.

10.

Determine if the suction pressure falls between normal operating limits using the Normal Refrigerant Suction Pressures chart illustration.

Courtesy of FORD MOTOR COMPANY

11.

Proceed to the Diagnostic Table below.

Diagnostic Table

NOTE: The following table is used to guide diagnosis of the refrigerant system if operating pressures are outside normal limits.

1.

Refer to the chart below.

High (Discharge) Pressure

Low (Suction) Pressure

Component - Causes

High or Clutch Cycling

High

Condenser - inadequate airflow.

High

Normal to High

Engine - overheating.

Normal to High

Normal

Refrigerant overcharge - air in refrigerant.

Normal to Low

Normal to High

A/C suction line - partially restricted or plugged.⁽¹⁾

Normal to Low

Low or Clutch Cycling

Low refrigerant charge, A/C suction line -partially restricted or plugged.⁽²⁾

Erratic Operation or Compressor Not Running

Evaporator discharge air temperature sensor or A/C pressure transducer - poor connection at A/C clutch connector. A/C electrical circuit erratic - see A/C Electrical Circuit Wiring Diagram.

Normal to Low

High

Compressor - low performance.

Additional Possible Cause Components Associated With Inadequate Compressor Operation

Compressor drive belt - loose
Compressor clutch - slipping
Clutch coil open - shorted, or loose mounting
HVAC module
Clutch wiring circuit - high resistance, open or blown fuse
Compressor operation interrupted by PCM

Additional Possible Cause Components Associated With a Damaged Compressor

Incorrect clutch air-gap
Refrigerant leaks

⁽¹⁾	Low pressure reading will be normal to high if restriction is downstream of service access valve.

⁽²⁾	Low pressure reading will be low if restriction is upstream of service access valve.