AC Hose - Low Side

This procedure covers the replacement of the low-side AC hose on a 2014-2018 Chevrolet Silverado 1500 with the 5.3L V8 EcoTec3 engine, including refrigerant recovery, hose removal, installation, and system recharge.

Warnings

Tools required

Parts

• AC low-side hose assembly × 1 — Use OEM specification (GM 84239855 or equivalent)
• AC line O-ring kit × 1 — Use OEM specification
• R134a refrigerant × 1 — Approximately 2.2 lbs total system capacity
• PAG 46 oil × 1 — AC compressor lubricant

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely if recently operated
3. Verify AC system is not running and turn ignition off
4. Gather all necessary tools and replacement parts
5. Ensure AC recovery/recharge machine is properly calibrated and contains sufficient fresh refrigerant
6. Inspect new AC hose for damage and verify correct part number matches vehicle application

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to service ports (low-side on accumulator and high-side on liquid line near firewall). Follow machine instructions to completely recover all R134a refrigerant from the system. Record the amount recovered for comparison during recharge. Allow system pressure to equalize to atmospheric pressure.
2. 2

   Access low-side hose connections
   Open hood and locate the low-side AC hose running from the accumulator (on passenger side near firewall) to the compressor (driver side of engine). The hose may run along the engine valley or around the front of the engine depending on model year. Remove any plastic engine covers if necessary for access. Note exact hose routing and locations of all retaining clips.
3. 3

   Disconnect hose at accumulator
   Using a line wrench to prevent rounding the fitting, loosen and remove the AC line fitting nut at the accumulator connection on the passenger side. Once loose, carefully unthread by hand and separate the connection. Remove and discard the old O-rings from both the hose and accumulator port. Immediately cap or cover both openings to prevent moisture and debris entry.
4. 4

   Disconnect hose at compressor
   Locate the low-side hose connection at the AC compressor on the driver side of the engine block. Use a line wrench on the fitting nut while holding the compressor port fitting with a backup wrench to prevent turning the port. Loosen and remove the fitting nut. Separate the connection and remove the old O-rings. Cap or cover both openings immediately.
5. 5

   Remove hose retaining clips and brackets
   Work along the length of the hose to release all retaining clips securing the hose to the engine, frame, or body. These may be plastic push clips or metal brackets. Take photos or make notes of exact clip positions for reinstallation. Remove any mounting brackets if bolted in place, keeping hardware organized.
6. 6

   Remove old low-side hose
   Carefully extract the low-side hose assembly from the engine bay, working it through any tight areas or around other components. Inspect the old hose for signs of damage, abrasion, or leaks to identify the failure mode. Compare the old hose to the new hose to verify correct replacement part.
7. 7

   Prepare new hose and fittings
   Inspect new hose for damage. Install new O-rings onto both ends of the new hose, ensuring they are properly seated in their grooves. Lightly coat each new O-ring with fresh PAG 46 oil (approximately 1-2 drops per O-ring) to aid sealing and prevent damage during assembly. Do not over-lubricate.
8. 8

   Route new hose into position
   Following the routing notes and photos from removal, carefully route the new low-side hose through the engine bay. Ensure the hose does not contact hot engine components, sharp edges, or moving parts. The hose should follow the original path without kinks, twists, or excessive bending. Install retaining clips and brackets in their original positions to secure the hose.
9. 9

   Connect hose to accumulator
   Remove the cap from the accumulator port. Ensure the new O-ring is properly seated on the hose fitting. Hand-thread the fitting nut onto the accumulator port, ensuring it threads smoothly without cross-threading. Once hand-tight, use a line wrench and torque wrench to tighten to specification.
   Torque spec

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

    Connect hose to compressor
    Remove the cap from the compressor port. Verify the new O-ring is properly seated on the hose fitting. Hand-thread the fitting nut onto the compressor low-side port, checking for smooth threading. Use a backup wrench on the compressor port and a line wrench with torque wrench on the fitting nut to tighten to specification.
    Torque spec

    AC Line Fittings20 Nm (15 lb-ft)
11. 11

    Add refrigerant oil to system
    Determine the amount of PAG 46 oil to add to the system. Typically, add the same amount of new oil as was recovered with the refrigerant, or follow manufacturer specifications (usually 2-3 oz for hose replacement). Add the specified amount of fresh PAG 46 oil through the low-side service port using an oil injector or through the recovery machine if equipped.
12. 12

    Evacuate AC system
    Connect the vacuum pump to the AC system through the service ports. Evacuate the system to a deep vacuum (minimum 29 inches Hg) for at least 30 minutes. This removes all moisture and air from the system. Monitor for vacuum hold - the system should maintain vacuum for at least 10 minutes after the pump is turned off. If vacuum drops, there is a leak that must be found and repaired.
13. 13

    Recharge AC system
    Using the AC recovery/recharge machine or manifold gauges, recharge the system with the specified amount of R134a refrigerant (approximately 2.2 lbs total, or amount recovered if less). Charge through the low-side port with the engine running and AC on MAX setting. Monitor pressures on both high and low sides to ensure proper fill. Do not overcharge the system.
14. 14

    Leak test and verify operation
    With the system charged, use an electronic leak detector or UV dye (if installed) to check all connections for leaks, paying special attention to the newly installed hose fittings at both the accumulator and compressor. Start the engine and turn AC to MAX cooling. Allow the system to run for 5-10 minutes. Verify cold air output from vents, check that compressor clutch engages properly, and monitor system pressures for normal operation.

Reassembly

1. Reinstall any engine covers or plastic shields removed for access
2. Double-check that all hose retaining clips and brackets are properly secured
3. Verify no tools or materials were left in the engine bay
4. Clean any spilled PAG oil from engine components

Verification

• Start engine and turn AC to MAX cooling with fan on high
• Verify cold air (typically 40-50°F) is discharged from center vents within 2-3 minutes
• Confirm AC compressor clutch engages and disengages properly during operation
• Check system pressures: Low-side should be 25-45 PSI and high-side 200-250 PSI at idle with ambient temperature 70-80°F
• Inspect all hose connections for signs of leaks, oil seepage, or frost buildup
• Verify low-side hose is not contacting any moving parts or hot surfaces
• Listen for abnormal noises from compressor or system operation
• Test AC performance during a short test drive to ensure sustained cooling

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