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A/C Pressure Zone "D" Diagnosis

WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. 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 Test Center (J-43600).
NOTE: Definition: The low side pressure is lower than normal and the high side pressure is higher than normal.
  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. Feel the liquid line before the orifice tube. Is the liquid line cold before the orifice tube? If so, go to next step. If not, go to step  8.
  3. Feel along the surfaces of the compressor discharge hose, the condenser and the liquid line between the condenser and the orifice tube. Did you detect an abrupt drop in temperature along the surfaces of any of the listed components? If so, go to step  7. If not, go to next step.
  4. Feel the liquid line at the orifice tube location for extreme cold, possibly accompanied by heavy frost. Feel along the liquid line beyond the orifice tube location for warm temperature. Is the liquid line extremely cold at the orifice tube location and warm beyond the orifice tube location? If so, go to step  11. If not, go to next step.
  5. Feel along the surfaces of the following components:
    • Evaporator inlet tube between the orifice tube and the evaporator core.
    • Evaporator outlet tube between the evaporator core and the compressor.
    • Accumulator and the compressor suction hose.
    Did you feel an abrupt temperature change along the surfaces of any of the listed components? If so, go to step  7. If not, go to next step.
  6. Feel along the surfaces of the low and the high side components:
    • The evaporator inlet tube between the orifice tube and the evaporator core.
    • The evaporator outlet tube between the evaporator core and the accumulator.
    • The accumulator.
    • The compressor suction hose.
    • The compressor discharge hose.
    • The condenser and the evaporator inlet tube between the condenser and the orifice tube.
    Are the temperatures of these components only mildly warm? If so, go to step  14. If not, go to step  8.
  7. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Remove the restriction from the component, or replace the component which produced an abrupt temperature drop. After repairs are complete, go to step  9.
  8. Recover the refrigerant and evacuate the system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Record the weight of the recovered refrigerant. Compare the weight of the recovered refrigerant with the system capacity. See SPECIFICATIONS . Is the weight of the recovered refrigerant charge greater than 75 percent of the total system capacity? If so, go to next step. If not, go to step  10.
  9. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Is the cooling performance improved? If so, go to step  21. If not, go to next step.
  10. Leak test the system. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Repair any leaks. After repairs are complete, go to step  21.
  11. The orifice tube is restricted. Remove the orifice tube and inspect. See ORIFICE TUBE  under REMOVAL & INSTALLATION. Are metal flakes present? If so, go to next step. If not, go to step  13.
  12. Remove the compressor hose assembly from the vehicle. Inspect the hose for debris by blowing shop air through one end of the hose while covering the other end with a shop towel. Observe the amount of debris collected in the shop towel. Did a large amount of debris collect in the shop towel? If so, go to step  18. If not, go to step  20.
  13. If the orifice tube was restricted with a brown or black residue, flush the A/C system and replace the accumulator. See ACCUMULATOR  under REMOVAL & INSTALLATION. After repairs are complete, go to step  21.
  14. Recover the refrigerant. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Disconnect the compressor hose from the compressor. See COMPRESSOR HOSE ASSEMBLY  under REMOVAL & INSTALLATION. Inspect for the presence of debris in the compressor suction port. Is debris present in the compressor suction port? If so, go to next step. If not, go to step  19.
  15. Remove the debris from the suction port. Inspect the orifice tube for damage or debris. Did you find evidence of damage or debris? If so, go to step  17. If not, go to next step.
  16. If the orifice tube does not show any signs of damage or debris, remove the compressor hose assembly from the vehicle. Inspect the hose for debris by blowing shop air through one end of the hose while covering the other end with a shop towel. Observe the amount of debris collected in the shop towel. Did a large amount of debris collect in the shop towel? If so, go to step  18. If not, go to step  19.
  17. Replace the orifice tube. See ORIFICE TUBE  under REMOVAL & INSTALLATION. If the orifice tube was restricted, observe the type of debris present. Are metal flakes present? If so, go to step  12. If not, go to step  13.
  18. If a large amount of debris was collected in the shop towel from the compressor hose assembly, replace the accumulator and install an A/C refrigerant filter. See ACCUMULATOR  and A/C REFRIGERANT FILTER  under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
  19. Install the compressor hose assembly. See COMPRESSOR HOSE ASSEMBLY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  21.
  20. Install the compressor hose assembly and install an A/C refrigerant filter. See A/C REFRIGERANT FILTER  under REMOVAL & INSTALLATION. Recharge the A/C system. See RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are complete, go to step  21.
  21. Record the low and the high side pressures and the panel outlet air 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. Are the readings within the specified ranges as shown on the A/C Performance Chart? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE TEST  under PERFORMANCE TESTS.
  22. 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.
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