Noise From A/C System - Chevrolet Trailblazer Service Manual

4. Listen to the blower motor at each blower speed. Is the blower motor making a
squeaking or chirping noise? If yes, go to step 8. If no noise exists, go to step 10.
5. Remove the blower motor, and inspect the blower motor and impeller for deposits
of foreign material. If there is debris, go to step 7. If there is no debris, go to the
next step.
6. Inspect the blower motor impeller for cracked blades, loose impeller retainer, or
improper impeller alignment. If any of these conditions exist, go to step 8. If none of
these exist, go to step 9.
7. Remove the foreign material, go to step 10.
8. Repair or replace blower motor or impeller as needed, go to step 10.
9. Install the blower motor, go to step 10.
10. Operate the system in order to verify the repair. If the condition has been corrected,
the repair is complete. If noise still exists, repeat the entire procedure.

Noise from A/C System

NOTE: Noise from the A/C system may be heard as squealing, chirping or moaning
noises, or as a vibration noise.
1. Start the engine and verify operation of the A/C system. If a screeching or
squealing noise heard when the A/C is engaged go to step 2. If not, go to step 8.
2. With engine OFF, inspect the drive belt for excessive wear. If the belt is
excessively worn, go to step 17. If the belt is not worn, go to step 3.
3. Inspect the drive belt tension. If the tension is correct, go to step 4. If the tension is
not correct, go to step 18.
4. Inspect the drive belt for excessive oil coverage. If the belt is covered with oil, go to
step 16. If there is no oil present, go to next step.
5. Start the engine, ensure the A/C system is ON, and visually inspect the
compressor and the clutch. If the compressor does not turn, go to step 23. If the
compressor and clutch are visually okay, go to step 6.
6. Check compressor clutch for slippage, if the compressor is slipping, go to step 22.
If the clutch is not slipping, go to step 7.
7. Using a stethoscope, listen to the A/C compressor for any abnormal noise. If noise
appears to be caused by the compressor, go to step 14. If the compressor is not
the cause of the noise, go to step 9.
8. Does a moaning noise exist when the A/C clutch is engaged? If yes, go to the next
step. If not, go to step 11.
9. Listen to the A/C compressor components and mounting for noise concerns using
a stethoscope. Are any of these components loose, damaged or excessively worn?
If yes, go to step 19. If no, go to the next step.
10. Idle the engine and engage the A/C compressor clutch. Using a stethoscope, move
around the entire refrigerant plumbing system. Listening for any abnormal noises
caused by a component of the A/C system touching another component. Are any of
the A/C components grounding out and causing a vibration noise? If yes, go to step
21. If no, go to step 12.
11. Does a vibration or rattle noise exist when the A/C clutch is engaged? If yes, go to
the next step. If no, go to step 13.
12. Does the noise stop when the A/C clutch is disengaged? If yes, go to step 14. If no,
go to step 24.