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A/C Pressure Zone "B" Diagnosis

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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).
  1. Were you sent here from the A/C System Performance Test? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE TEST  under PERFORMANCE TESTS.
  2. After continued operation of the A/C system, do the low and the high side pressures equalize or become static? If so, go to step  5. If not, go to next step.
  3. Refer to the pressures recorded during the A/C System 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 or Figure .
    • The high side pressure is less than the specified pressure range of the A/C Performance Table. See Figure or 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.
  4. Refer to the pressures recorded during the A/C System 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 or Figure .
    • The high side pressure is less than the specified pressure range of the A/C Performance Table. See Figure or 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, See A/C SYSTEM PERFORMANCE TEST  under PERFORMANCE TESTS.
  5. 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 complete, go to next step.
  6. Record the low and the high side pressures as well as the I/P panel air outlet temperature after you perform the repairs. Compare the pressures and the panel outlet temperature to those listed in the A/C Performance Chart. See Figure or Figure . Are the readings within the specified ranges found on the A/C Performance Chart? If so, go to step  13. If not, go to next step.
  7. 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.
  8. 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.
  9. Remove the suction and the discharge lines from the compressor. See SUCTION HOSE  and DISCHARGE HOSE  under REMOVAL & INSTALLATION. Inspect for metal flake contamination at the line connections and the compressor ports. Remove the compressor hose from the compressor. 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.
  10. Replace the A/C compressor. See COMPRESSOR  under REMOVAL & INSTALLATION. Install an A/C refrigerant filter. See A/C REFRIGERANT FILTER  under REMOVAL & INSTALLATION. Replace the orifice tube. See ORIFICE TUBE  under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repair is complete, go to step  13.
  11. Flush the A/C system. See FLUSHING PROCEDURES in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Replace the orifice tube. See ORIFICE TUBE  under REMOVAL & INSTALLATION. Replace the A/C compressor. See COMPRESSOR  under REMOVAL & INSTALLATION. Replace the accumulator. See ACCUMULATOR  under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step  13.
  12. 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. After repairs are complete, go to next step.
  13. Operate the system in order to verify the repair. Did you find and correct the condition? If so, system is okay. If not, go to SYMPTOM TESTS .
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