How to replace Compressor on Chevrolet Trailblazer, GM Envoy and Buick Rainier?

The Procedure is Exactly Similar for Chevy, Envoy & Buick car models.

Compressor Removal & Installation details as per Engine models is as follows.The procedure is for 4.2L engine, 5.3L & 6.0L engine models.

4.2L Engine

CAUTION

Before beginning this procedure, refer to the precautions at the beginning of this section. Only a MVAC-trained, EPA-certified, automotive technician should service the A/C system or its components.

1. Disconnect the negative battery cable.
2. Recover the refrigerant., as outlined in this section
3. Remove the alternator, as outlined in the Engine Electrical Section.
4. Remove the idler pulley.
5. Disconnect the compressor electrical connectors.
   
   NOTE

   Some system pressure may still exist in the A/C compressor crankcase after you evacuate the system.
6. Remove the compressor hose assembly bolt from the compressor.
7. Remove the compressor hose assembly block from the compressor.
8. Remove the compressor mounting bolts from the compressor.
9. Remove the compressor .
10. Drain and measure the compressor oil, as follows:
    
    NOTE

    Drain and measure as much of the refrigerant oil as possible from the removed compressor.
    
    
    1. Drain the oil from both the suction and discharge ports of the removed compressor into a clean, graduated container. Rotate the compressor shaft to assist in draining the compressor.
    2. Measure and record the amount of oil drained from the removed compressor. This measurement will be used during installation of the replacement compressor.
    3. Properly discard the used refrigerant oil.
       
       NOTE

       The refrigerant oil in the A/C system must be balanced during compressor replacement.
    4. The replacement compressor is shipped with 240 ml (8.0 oz) of refrigerant oil.
    5. Before installing the compressor, the refrigerant oil will have to be partially drained:
    6. Refer to the amount of refrigerant oil recorded during the compressor removal.
    7. Subtract the amount recorded from the total system capacity.
    8. The difference between the total system capacity and the recorded amount is the calculated amount to be drained from the replacement compressor.
    9. Drain the calculated amount of refrigerant oil from the replacement compressor.

To install:

1. Install the compressor mounting bolts to the compressor and tighten to 37 ft. lbs. (50 Nm).
2. Install the compressor hose assembly block to the compressor.
3. Install the compressor hose assembly bolt to the compressor. Tighten the bolt to 24 ft. lbs. (33 Nm).
4. Connect the compressor electrical connectors.
5. Install the idler pulley.
6. Install the alternator.
7. Evacuate and recharge the A/C system.
8. Leak test the fittings of the components.

5.3L & 6.0L Engines

CAUTION

Before beginning this procedure, refer to the precautions at the beginning of this section. Only a MVAC-trained, EPA-certified, automotive technician should service the A/C system or its components.

1. Recover the refrigerant, as outlined in this section.
2. Remove the washer solvent container.
3. Remove the air cleaner resonator outlet duct.
4. Remove the cooling fan and shroud.
5. Release the tension on the air conditioning drive belt.
6. Reposition the air conditioning drive belt from the compressor pulley.
7. Remove the compressor hose assembly nut from the compressor.
8. Remove the compressor hose assembly from the compressor.
9. Remove the upper A/C compressor mounting bracket bolts.
10. Remove the lower coolant hose.
11. Raise the vehicle.
12. Disconnect the electrical connection from the compressor.
13. Turn the right tire to gain access to the remaining compressor mounting bolts.
14. Remove the lower A/C compressor mounting bracket bolts.
15. Lower the vehicle.
16. Reposition the compressor and mounting bracket to access the remaining compressor to bracket bolts.
17. Remove the upper A/C compressor mounting bolts.
18. Remove the A/C compressor.
19. Remove the A/C compressor bracket.
20. If replacing the A/C compressor, the replacement compressor must be balanced, as follows:
    
    NOTE

    Drain and measure as much of the refrigerant oil as possible from the removed compressor.
    
    
    1. Drain the oil from both the suction and discharge ports of the removed compressor into a clean, graduated container. Rotate the compressor shaft to assist in draining the compressor.
    2. Measure and record the amount of oil drained from the removed compressor. This measurement will be used during installation of the replacement compressor.
    3. Properly discard the used refrigerant oil.
       
       NOTE

       The refrigerant oil in the A/C system must be balanced during compressor replacement.
    4. The replacement compressor is shipped with 240 ml (8.0 oz) of refrigerant oil.
    5. Before installing the compressor, the refrigerant oil will have to be partially drained:
    6. Refer to the amount of refrigerant oil recorded during the compressor removal.
    7. Subtract the amount recorded from the total system capacity.
    8. The difference between the total system capacity and the recorded amount is the calculated amount to be drained from the replacement compressor.
    9. Drain the calculated amount of refrigerant oil from the replacement compressor.

To install:

1. Add the proper amount of PAG oil to the compressor crankcase.
2. Position the A/C compressor mounting bracket partially into the vehicle.
3. Position the A/C compressor partially into the vehicle.
4. Install the upper compressor mounting bolts into the compressor mounting bracket. Tighten the upper rear bolts to 37 ft. lbs. (50 Nm).
5. Install the upper compressor mounting bolts into the compressor and bracket assembly.
6. Position the compressor and bracket assembly into the correct location on the engine.
7. Tighten the upper compressor mounting bolts to 37 ft. lbs. (50 Nm).
8. Raise the vehicle
9. Start the lower compressor mounting bolts. Tighten the bolts to 37 ft. lbs. (50 Nm).
10. Connect the electrical connector to the A/C compressor.
11. Raise the vehicle.
12. Install the lower coolant hose.
13. Install the compressor hose assembly to the compressor.
14. Install the compressor hose assembly nut to the compressor. Tighten the nut to 12 ft. lbs. (16 Nm).
15. Install the accessory drive belt to the tensioner.
16. Install the cooling fan and shroud.
17. Install the air cleaner resonator outlet duct.
18. Install the washer solvent container.
19. Fill the cooling system.
20. Evacuate and recharge the A/C system.
21. Leak test the fittings of the component.

These details will help.

Thanks.

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Car repair guide?

http://technoanswers.blogspot.in/2012/03/car-repair-guide.html