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A/C Pressure Zone "B" Diagnosis

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. 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: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
NOTE: Tools Required: ACR 2000 Air Conditioning Service center (J-43600).
NOTE: Definition: The low side pressure is higher than normal and the high side pressure is lower than normal.
  1. Were you sent here from the A/C PERFORMANCE TEST? If so, go to next step. If not, go to A/C PERFORMANCE TEST .
  2. 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.
  3. Refer to the pressures recorded during the A/C PERFORMANCE TEST. Inspect for the following conditions:
    • The low side pressure equal to or above the specified pressure range of the A/C performance table.
    • The high side pressure is below the specified pressure range of the A/C performance 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. If not, go to next step.
  4. Refer to the pressures recorded during the A/C PERFORMANCE TEST t. Inspect for the following conditions:
    • The Low Side Pressure Is Above The Specified Pressure Range Of The A/C PERFORMANCE  table.
    • The High Side Pressure Is Below The Specified Pressure Range Of The A/C PERFORMANCE  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 PERFORMANCE TEST .
  5. The A/C system has a low refrigerant charge. Evacuate and recharge the A/C system. See RECOVERY, EVACUATING & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to next step.
  6. After you perform the repairs, record the following information:
    • The low and the high side pressures.
    • The I/P outlet air temperature.
    Compare the pressures and the temperature to those listed in Figure. Are the readings within the specified ranges? 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. Are there 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 there a brown, powdery residue present? If so, go to step  11. If not, go to step  12.
  9. 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 there metal flake contamination present? If so, go to step  12. If not, go to step  12.
  10. Replace the A/C compressor. See COMPRESSOR  under REMOVAL & INSTALLATION. Install an A/C refrigerant filter. See REFRIGERANT FILTER  under REMOVAL & INSTALLATION. Replace the orifice tube. See ORIFICE TUBE  under REMOVAL & INSTALLATION. Evacuate and recharge the A/C system. See RECOVERY, EVACUATING & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Is the repair complete? If so, go to next step.
  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, EVACUATING & 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, EVACUATING & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step  13.
  13. Operate the system in order to verify the repair Did you correct the condition? If so, system is okay. If not, go to step  2.
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