A/C Pressure Zone "B" Diagnosis

WARNING: This page is about a different car, the 2002 Chevrolet Malibu. 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 PERFORMANCE TEST 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 pressure range of the A/C Performance Table. See Figure.
- The high-side pressure is less than the specified pressure range of the A/C Performance Table. See Figure.
- 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. 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 greater than the specified pressure range of the A/C Performance Table. See Figure.
- The high-side pressure is less than the specified pressure range of the A/C Performance Table. See Figure.
- 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 PERFORMANCE TEST under PERFORMANCE TESTS.
The A/C system has a low refrigerant charge. Evacuate and recharge the A/C system. Go to next step.
Record the low and high side pressures and the I/P panel outlet air temperature after repairs are performed. Compare the pressures and the outlet temperature to those listed in the A/C Performance Chart. See Figure. Are the readings within the specified ranges? 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 TUBE 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? If so, go to next step. If not, go to step 12.
Replace the A/C compressor. See COMPRESSOR under REMOVAL & INSTALLATION. Replace the orifice tube. See ORIFICE TUBE under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. After repairs are complete, go to step 13.
Flush the A/C system. See FLUSHING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Replace the accumulator, compressor and the orifice tube. See ACCUMULATOR , COMPRESSOR and ORIFICE TUBE . Evacuate and recharge the A/C system. After repairs are complete, go to step 13.
Replace the A/C compressor. See COMPRESSOR under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Go to next step.
Operate the system in order to verify the repair Did you find and correct the condition? If so, go system is okay. If not, go to SYMPTOM DIAGNOSIS under TROUBLE SHOOTING.