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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heater Systems >> Symptom Tests >> Test "F": HVAC Module Noise

Test "F": HVAC Module Noise

  1. Were you sent here from SYMPTOM DIAGNOSIS? If so, go to next step. If not, go to SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
  2. Start the engine. Cycle through all of the following:
    • Blower Motor Speeds
    • HVAC Modes
    • Temperature Control Settings
    Determine the type of noise. Scrape, pop, tick/click, chirp or groaning or air rush/whistle Is a scrape or pop noise evident when selecting modes or temperature settings? If so, go to step  6. If not, go to next step.
  3. Is a tick/click, chirping, groaning or scraping noise present, but decreases as blower motor speed is decreased? If so, go to step  6. If not, go to next step.
  4. Is an air rush/whistle noise evident in all modes but not all temperature settings? If so, go to step  6. If not, go to next step.
  5. Is an air rush/whistle noise evident only in defrost or floor mode? If so, go to next step. If not, go to next step.
  6. Remove the Instrument Panel (I/P) carrier. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After removal, go to next step.
  7. Inspect the air flow doors for proper operation. Inspect the ducts for obstructions or foreign materials. Were any of these conditions found? If so, go to step  10. If not, go to next step.
  8. Inspect the mode and temperature doors and seals for warping or cracking. Are the doors in normal condition? If so, go to next step. If not, go to step  12.
  9. Replace the appropriate door and/or seals. See REMOVAL & INSTALLATION . After repairs, go to step  11.
  10. Remove any obstructions or foreign material found. After repairs, go to step  11.
  11. Install the I/P carrier. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to step  12.
  12. Operate the system to verify the repair. Is the noise gone? If so, system is okay. If not, go to step  2.
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