AC Compressor

This procedure covers the removal and replacement of the AC compressor on a 2019 Chevrolet Impala with the 3.6L V6 LFX engine, including refrigerant recovery, compressor replacement, and system recharge.

Warnings

Tools required

Parts

• AC compressor × 1 — Use OEM specification
• AC line O-rings × 4 — Use OEM specification
• Serpentine belt × 1 — Use OEM specification
• PAG oil for AC compressor × 1 — PAG 46 or OEM equivalent

Fluids

• R-134a refrigerant

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery cable and wait 2 minutes for airbag system to discharge
4. Raise and safely support front of vehicle on jack stands
5. Remove engine splash shield from underneath vehicle

Procedure

1. 1

   Recover AC refrigerant
   Connect AC recovery machine to service ports on high and low side lines. Follow machine manufacturer instructions to fully recover all refrigerant from the system. Record the amount of refrigerant and oil recovered for reference during recharge. Verify system pressure is at atmospheric pressure before proceeding.
2. 2

   Remove serpentine belt
   Locate the serpentine belt tensioner on the front of the engine. Using a serpentine belt tool, rotate the tensioner clockwise to release tension. Slide the belt off the AC compressor pulley first, then remove it from all other pulleys. Inspect belt for wear, cracks, or glazing and replace if necessary. Do not reuse a belt with more than 30,000 miles or visible damage.
3. 3

   Disconnect AC compressor electrical connector
   Locate the electrical connector on the AC compressor clutch assembly. Press the locking tab and pull the connector straight off the compressor. If present, remove the bolt securing the connector bracket using a 10mm socket.
   Torque spec

   Clutch Connector Bolt8 Nm (6 lb-ft)
4. 4

   Disconnect AC line fittings from compressor
   Using a 16mm wrench, loosen and remove the discharge line fitting from the top rear of the compressor. Then remove the suction line fitting from the front of the compressor. Cap or plug all open fittings immediately to prevent moisture and debris contamination. Inspect O-rings on the lines and discard them - new O-rings must be installed during reassembly.
5. 5

   Remove AC compressor mounting bolts
   The AC compressor is secured to the engine block with 3 mounting bolts. Using a 13mm socket, remove all 3 bolts from the compressor mounting bracket. Support the compressor weight as you remove the final bolt to prevent it from falling.
6. 6

   Remove AC compressor from vehicle
   Carefully maneuver the AC compressor down and out from underneath the vehicle. The compressor is heavy and awkward to handle - use caution to avoid dropping it or damaging surrounding components. Drain any residual oil from the old compressor into a drain pan and measure the amount for reference.
7. 7

   Prepare new AC compressor
   Remove shipping caps from the new compressor ports. Drain the shipping oil from the new compressor into a graduated container to measure the amount. Add fresh PAG oil to the new compressor in an amount equal to what was drained from the old compressor (typically 60-90ml). If the old compressor oil was contaminated or excessive amount drained, consult service information for proper fill quantity. Rotate the compressor clutch hub by hand several times to distribute the oil internally.
8. 8

   Install new AC compressor
   Position the new AC compressor into the mounting bracket from underneath the vehicle. Align all mounting bolt holes. Hand-thread all 3 mounting bolts before tightening any of them. Once all bolts are started, tighten them in a star pattern to the specified torque value using a torque wrench.
   Torque spec

   AC Compressor Mounting Bolts25 Nm (18 lb-ft)
9. 9

   Install new O-rings and connect AC lines
   Coat new O-rings with a thin layer of PAG oil and install them into the grooves on both AC line fittings. Do not reuse old O-rings. Position each line to the compressor and hand-thread the fittings to ensure proper alignment. Tighten the discharge line fitting and suction line fitting to the specified torque using a torque wrench. Do not overtighten as this can damage the O-rings or aluminum threads.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
10. 10

    Reconnect electrical connector
    Push the electrical connector onto the AC compressor clutch coil terminals until it clicks into place. If equipped with a connector bracket bolt, install and tighten it to specification.
    Torque spec

    Clutch Connector Bolt8 Nm (6 lb-ft)
11. 11

    Install serpentine belt
    Route the new serpentine belt around all pulleys following the belt routing diagram on the fan shroud or under the hood. Ensure the belt is properly seated in all pulley grooves. Using the serpentine belt tool, rotate the tensioner clockwise and slide the belt onto the final pulley. Release the tensioner slowly to apply proper tension to the belt.
12. 12

    Evacuate AC system
    Connect a vacuum pump to the AC system service ports. Evacuate the system to 29.9 inches of mercury (full vacuum) and hold for at least 30 minutes. Monitor for any vacuum loss which would indicate a leak. If vacuum holds steady, the system is sealed and ready for recharge.
13. 13

    Recharge AC system
    Using approved AC recharge equipment and refrigerant scale, add R-134a refrigerant to the system according to the specification on the underhood label (typically 24-28 oz for this vehicle). Add refrigerant slowly through the low-side port only with engine running and AC on MAX. Monitor system pressures during charging. Do not exceed the specified refrigerant amount.

Reassembly

1. Reinstall engine splash shield
2. Lower vehicle from jack stands
3. Reconnect negative battery cable
4. Verify all tools and parts have been removed from engine compartment

Verification

• Start engine and turn AC to MAX with blower on high
• Verify AC compressor clutch engages and disengages properly
• Check for abnormal noises from the compressor or belt area
• Verify cold air is blowing from vents within 2-3 minutes
• Inspect all AC line connections for refrigerant leaks using an electronic leak detector
• Check system pressures with AC gauges - low side should be 25-35 PSI and high side should be 200-250 PSI at idle with 70°F ambient temperature
• Verify serpentine belt is properly seated and tracking correctly on all pulleys

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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