A/C Pressure Zone "B" Diagnosis

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.

NOTE: Tools Required: ACR 2000 Air Conditioning Service Center (J-43600) or equivalent.

NOTE: DEFINITION: The low side pressure is higher than normal and the high side pressure is lower than normal.

Were you sent here from the A/C performance test? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE under PERFORMANCE TESTS.
After continued operation of the A/C system, do the low and high side pressures equalize or become static? If so, go to step 5. If not, go to next step.
Refer to the pressures recorded during the A/C Performance Test. Inspect for the following conditions:
- The low side pressure is equal to or greater than the specified. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE) or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE) table.
- The high side pressure is below the specified pressure range of the A/C Performance Table. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE) or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE) table.
- The low side refrigerant line at the compressor feels cool-to-warm.
- The high side refrigerant line at the compressor feels warm-to-hot.
Do the listed conditions exist? If so, go to step 5. In not, go to next step.
Refer to the pressures recorded during the A/C Performance Test. Inspect for the following conditions:
- The low side pressure is greater than the specified pressure range of the A/C Performance Table. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE) or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE) table.
- The high side pressure is less than the specified pressure range of the A/C Performance Table. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE) or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE) table.
- The low side refrigerant line at the compressor feels warm.
- The high side refrigerant line at the compressor feels warm-to-hot.
Do the listed conditions exist? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE under PERFORMANCE TESTS.
The A/C system has a low refrigerant charge. Evacuate and recharge the A/C system. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are completed, go to next step.
After you perform the repairs, record the following information:
- The low and the high side pressures.
- The instrument panel outlet air temperature.
Compare the pressures and the temperature to those listed in the A/C performance table. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE) or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE) table. Are the readings within the specified ranges found on the A/C performance table? If so, go to step 13. If not, go to next step.
The A/C compressor is malfunctioning. Remove the orifice tube and inspect for contamination. See ORIFICE SOLENOID & SCREEN under REMOVAL & INSTALLATION. Did you find metal flakes on the orifice tube? If so, go to step 9. If not, go to next step.
Inspect the orifice tube for a Brown, powdery residue indicating desiccant in the A/C system. Is a Brown, powdery residue present? If so, go to step 11. If not, go to step 12.
Remove the Compressor Hose from the Compressor. See COMPRESSOR HOSE under REMOVAL & INSTALLATION. Inspect for metal flake contamination at the line connections and the compressor ports. Is metal flake contamination present? Go to next step.
Replace the following components:
- A/C Compressor. See COMPRESSOR under REMOVAL & INSTALLATION.
- Orifice Solenoid. See ORIFICE SOLENOID & SCREEN under REMOVAL & INSTALLATION.
Evacuate and recharge the A/C system. After repairs are completed, go to step 13.
Flush the A/C system. See FLUSHING PROCEDURES in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Replace the following components:
- Orifice Solenoid. See ORIFICE SOLENOID & SCREEN under REMOVAL & INSTALLATION.
- A/C Compressor. See COMPRESSOR under REMOVAL & INSTALLATION.
- Accumulator. See ACCUMULATOR under REMOVAL & INSTALLATION.
Evacuate and recharge the A/C system. After repairs are completed, go to step 13.
Replace the A/C compressor. See COMPRESSOR under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. After repairs are completed, go to step 13.
Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to SYMPTOM DIAGNOSIS under TROUBLE SHOOTING.