LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 25 (HVAC Systems - Automatic) >> System Tests >> A/C Pressure Zone "A" Diagnosis

A/C Pressure Zone "A" Diagnosis

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. 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.
  1. Were you sent here from the A/C System Performance Test? If so, go to next step. If not, see A/C SYSTEM PERFORMANCE .
  2. Refer to the air outlet temperatures recorded during the A/C system performance test. Is there a 2-3° difference or more in the discharge air temperature between the right and left center I/P outlets? If so, go to step  7. If not, go to next step
  3. Did the customer concern mention that the A/C system output temperatures are good at first, but then turn warm during extended drives? If so, go to next step. If not, go to step  5.
  4. Increase engine speed to 2000 RPM. During extended operation of the A/C system, does the low side pressure decrease (possibly accompanied by heavy frost on the liquid line between the orifice tube and the evaporator)? If so, see A/C PRESSURE ZONE "D" DIAGNOSIS . If not go to next step.
  5. Refer to the pressures recorded during the A/C performance test. Inspect for the following conditions:
    • The high side pressure slightly above the specified pressure ranges but still within zone "A" on the A/C Pressure-Zone Classification Chart. See A/C SYSTEM PERFORMANCE .
    • The discharge line is hot.
    • The suction line is cool.
    Do the listed conditions exist? If so, go to step  7. If not, go to next step.
  6. Refer to the pressures recorded during the A/C performance test. Inspect for the following conditions:
    • The low side pressure slightly lower than the specified pressure ranges but still within zone "A" on the A/C Pressure-Zone Classification Chart. See A/C SYSTEM PERFORMANCE .
    • The discharge line is warm-to-hot.
    • The suction line is cool-to-warm.
    Do the listed conditions exist? If so, go to step  8. If not, go to TEST O: TEMPERATURE IS TOO HOT IN VEHICLE  under SYMPTOM TESTS.
  7. The A/C system may be undercharged. Leak test A/C system. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Recharge the A/C system to specifications. See GENERAL MOTORS in RECOVERY, EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING under HVAC. After repairs are completed, go to step  14.
  8. The A/C system may be contaminated. View the ACR 2000 Air Conditioning Service Center information screen for detection of foreign gases in the A/C system. Do foreign gases exist? If so, go to next step. If not, go to step  10.
  9. Evacuate the A/C system to a scavenging tank. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING under HVAC. Recharge the A/C system to specifications. After repairs are completed, go to step  14.
  10. The A/C system may contain too much moisture or air. Evacuate and recharge the A/C system to specifications. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING under HVAC. Operate the A/C system and check the outlet air temperatures. Are the outlet temperatures within the specified ranges of the A/C Performance Table? If so, go to step  15. If not, go to next step.
  11. The A/C system may contain too much refrigerant oil. Recover the refrigerant from the A/C system. See RECOVERY/EVACUATION & RECHARGING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING under HVAC. Remove the Accumulator. See ACCUMULATOR  under REMOVAL & INSTALLATION. Drain and measure the refrigerant oil from the Accumulator. Was there more than 5 oz. (148 ml) of refrigerant oil drained from the Accumulator? If so, go to next step. If not, go to step  13.
  12. Reinstall the Accumulator. Flush the A/C system. See FLUSHING PROCEDURES in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING. Add the specified amount of refrigerant oil to the Accumulator. See SPECIFICATIONS . Recharge the A/C system. After repairs are completed, go to step  14.
  13. Add the specified amount of refrigerant oil to the Accumulator. See SPECIFICATIONS . Install the accumulator. Recharge the A/C system. After repairs are completed, go to next step.
  14. Record the low and high side pressures and the I/P panel outlet air temperature. Compare the outlet temperatures to those listed in the A/C performance table. See A/C PERFORMANCE SPECIFICATIONS (3.5L V6 ENGINE)  or A/C PERFORMANCE SPECIFICATIONS (4.0L V8 ENGINE)  table. Are the high and low side pressures and outlet temperatures within specifications? If so, go to next step. If not, go to A/C SYSTEM PERFORMANCE  under PERFORMANCE TESTS.
  15. 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.
scientia non olet · About LEMON Manuals