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A/C Pressure Zone "C" Diagnosis

WARNING: Avoid contact with moving parts and hot surfaces while working around a running engine in order to prevent physical injury.
NOTE: Definition: The low and the high side pressures are both higher than normal.
  1. Were you sent here from the A/C PERFORMANCE TEST? If so, go to next step. If not, see A/C PERFORMANCE TEST  under PERFORMANCE TESTS.
  2. With the engine idling, turn ON the A/C. Inspect for proper cooling fan operation. Is the cooling fan operating properly? If so, go to next step. If not, go to step  5.
  3. Visually inspect for the following:
    • Restricted Air Flow
    • Damaged Condenser Cooling Fins
    • Inspect For Missing Or Misaligned Air Baffles
    Do any of the above conditions exist? If so, go to next step. If not, go to step  6.
  4. Repair the air flow restriction. After repairs are completed, go to step  9.
  5. Repair the cooling fan operation fault. See appropriate ENGINES or COOLING SYSTEMS article. After repairs are completed, go to step  9.
  6. Feel the liquid line on both sides of the orifice tube. Is the temperature the same before and after the orifice tube? If so, go to next step. If not, go to step  8.
  7. Replace the damaged/faulty orifice tube. See ORIFICE TUBE  under REMOVAL & INSTALLATION. After repairs are completed, go to step  9.
  8. Air is in the refrigerant system, or the system is overcharged. See the view screen on the ACR 2000 Refrigerant Station for foreign gas content in the refrigerant. Recover and recharge the A/C system. See RECOVERY, EVACUATING & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. After repairs are completed, go to step  9.
  9. Record the low and high side pressures and the I/P outlet air temperature after repairs are performed. Compare the pressures and outlet temperature to those listed in the A/C SYSTEM PERFORMANCE CHART. See Figure. Are the readings within the specified ranges? If so, go to next step. If not, see A/C PERFORMANCE TEST  under PERFORMANCE TESTS.
  10. 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 DIAGNOSIS  under TROUBLE SHOOTING.
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