| General Procedures Special Tool(s) | | R-134a Refrigerant Center 176-00002 or equivalent | | | R-134a Refrigerant Center 023-00174 or equivalent | | | R-134a Manifold Gauge Set 023-00047 or equivalent | Procedure 1 — 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 temperature. If the ambient temperature is 38°C (100°F) or less, follow Procedure 1. If the ambient temperature is greater than 38°C (100°F), follow Procedure 2. NOTE:If the A/C compressor cycles at any time during this test, refer to the diagnostic table. | | -
Drive the vehicle or run the engine until it reaches a normal operating temperature. | | | -
Connect a manifold gauge set or refrigerant center with high-pressure and low-pressure gauges to the refrigerant system. | | | -
Set the climate controls. - Set the A/C controls to MAX A/C, full COOL temperature, and the blower motor to HI.
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Open all the vehicle windows and leave the hood open for the test. Open the rear hatch and the rear doors. | | | -
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. | | | -
Record the ambient temperature. | | | -
Record the discharge pressure. If the pressure is fluctuating, record the average value. | | | -
Determine if the discharge pressure falls within the normal operating limits using the Normal Refrigerant Discharge Pressures chart. | | | -
Record the suction pressure. If the pressure is fluctuating, record the average value. | | | -
Determine if the suction pressure falls between normal operating limits using the Normal Refrigerant Suction Pressures chart. | | | -
Proceed to the diagnostic table. | Procedure 2 — Ambient Temperature Above 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 temperature. If the ambient temperature is 38°C (100°F) or less, follow Procedure 1. If the ambient temperature is greater then 38°C (100°F), follow Procedure 2. | | -
Drive the vehicle or run the engine until it reaches a normal operating temperature. | | | -
Connect a manifold gauge set or refrigerant center with high-pressure and low-pressure gauges to the refrigerant system. | | | -
Set the climate controls. - Set the A/C controls to MAX A/C mode, full COOL temperature, and the blower motor to M1.
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Open all the vehicle windows and leave the hood open for the test. Open the rear hatch and/or rear doors (if equipped). | | | -
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. | | | -
Record the ambient temperature. | | | -
Record the discharge pressure. If the pressure is fluctuating, record the average value. | | | -
Determine if the discharge pressure falls within the normal operating limits using the Normal Refrigerant Discharge Pressures chart. | | | -
Record the suction pressure. If the pressure is fluctuating, record the average value. | | | -
Determine if the suction pressure falls between normal operating limits using the Normal Refrigerant Suction Pressures chart. | | | -
Proceed to the diagnostic table. | Diagnostic Table | | -
NOTE:The following table is used to guide diagnosis of the refrigerant system if the operating pressures are outside the normal limits. Proceed to the diagnostic table. | 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 | High | Fixed orifice tube — missing O-rings leaking/missing | | Normal to low | Normal to high | A/C suction line — partially restricted or plugged a | | Normal to low | Low or clutch cycling | Low refrigerant charge, A/C suction line — partially restricted or plugged b A/C cycling switch — sticking closed | | Erratic operation or compressor not running | A/C cycling switch — poor connection at the A/C clutch connector or clutch cycling switch connector. A/C electrical circuit erratic — see the 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
- Control assembly switch — dirty contacts or sticking open
- Clutch wiring circuit — high resistance, open or blown fuse
- Compressor operation interrupted by the PCM
| | Additional Possible Cause Components Associated With a Damaged Compressor | - Incorrect clutch air-gap
- Suction accumulator — refrigerant oil bleed hose plugged
- Refrigerant leaks
| a Low pressure reading will be normal to high if the pressure is taken at the accumulator and if the restriction is downstream of the access valve. b Low pressure reading will be low if the pressure is taken near the compressor and the restriction is upstream of the access valve | |
