AC Hose - High Side

This procedure covers the replacement of the high-side AC hose on the 2016-2021 Honda Civic with 1.5L turbo engine, including refrigerant recovery, hose removal, and system recharge.

Warnings

Tools required

Parts

• High-side AC hose assembly × 1 — Use OEM Honda part number specific to model year
• AC line O-rings × 4 — Included with hose or purchase separately
• PAG 46 refrigerant oil × 1 — Honda-approved PAG oil
• R-134a refrigerant × 1 — Approximately 18 oz total system capacity

Preparation

1. Park vehicle on level surface and ensure engine is completely cold
2. Verify you have proper AC recovery/recharge equipment and EPA certification
3. Gather all tools, new AC hose, O-rings, and PAG oil before starting
4. Place wheel chocks behind rear wheels if raising front of vehicle

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to both high and low-side service ports. Follow machine manufacturer instructions to completely recover all refrigerant from the system. Record the amount of oil recovered for refill calculation. Wait until system reaches zero pressure before proceeding.
   ⚠️Do not proceed until refrigerant is completely recovered and system is at atmospheric pressure
2. 2

   Remove engine cover
   Pull upward on the engine cover to release the retaining clips. Lift the cover away to expose the turbocharger and AC line routing on the driver's side of the engine bay.
3. 3

   Access high-side hose at condenser
   The high-side hose runs from the compressor (on lower driver's side of engine) to the condenser (front of vehicle). Remove the plastic undertray beneath the front bumper using 10mm bolts if better access is needed. Locate the high-side line connection at the condenser near the passenger side of the radiator support.
4. 4

   Disconnect hose at condenser
   Using a 17mm wrench, carefully loosen the high-side line fitting at the condenser. Once loosened, unthread by hand and remove the fitting. Immediately cap or plug both the condenser port and hose end to prevent moisture and debris contamination. Remove and discard the old O-rings.
   ⚠Do not use excessive force on aluminum AC fittings as they can strip easily
5. 5

   Disconnect hose at compressor
   Locate the high-side line connection at the top of the AC compressor on the lower driver's side of the engine. Use a 14mm wrench to loosen and remove the fitting bolt. Separate the hose from the compressor. Cap or plug both the compressor port and hose end immediately. Remove and discard the old O-rings.
6. 6

   Remove hose mounting brackets
   Trace the high-side hose routing and locate all mounting brackets or clips securing it to the engine or chassis. Remove the 10mm bolts holding any brackets. Note the exact routing path and bracket positions for reinstallation of the new hose.
7. 7

   Remove old high-side hose
   Carefully maneuver the old high-side hose out of the engine bay, noting how it routes around other components. The hose typically passes near the turbocharger and behind the engine. Take photos if needed to document the routing path.
8. 8

   Prepare new high-side hose
   Unpack the new high-side hose and verify it matches the old hose configuration. Install new O-rings on both connection points (condenser end and compressor end). Lightly coat each new O-ring with fresh PAG 46 oil using a clean finger. Add approximately 1-2 ounces of fresh PAG oil into the new hose through one end, then rotate to coat the interior.
   ℹ️Use only refrigerant-grade PAG oil; do not use regular lubricants
9. 9

   Route new hose into position
   Following the routing path documented during removal, carefully install the new high-side hose into the engine bay. Ensure the hose does not contact the turbocharger, exhaust components, or any sharp edges. Position both ends near their respective connection points without forcing.
10. 10

    Connect hose to compressor
    Remove the cap from the compressor port and hose end. Verify the O-ring is properly seated in the hose fitting. Hand-thread the fitting onto the compressor until it seats, then use a torque wrench with 14mm socket to tighten to specification.
    Torque spec

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

    Connect hose to condenser
    Remove the cap from the condenser port and hose end. Verify the O-ring is properly seated in the hose fitting. Hand-thread the fitting onto the condenser until it seats, then use a torque wrench with 17mm socket to tighten to specification.
    Torque spec

    AC Line Fittings20 Nm (15 lb-ft)
12. 12

    Reinstall mounting brackets
    Secure the new high-side hose using all original mounting brackets and clips. Install and tighten the 10mm bolts to secure brackets, ensuring the hose follows the proper routing path without kinks or excessive tension.
13. 13

    Vacuum and leak test system
    Connect the AC machine to service ports. Pull a vacuum on the system for at least 45 minutes to remove all moisture and air. The system should hold vacuum without loss for at least 30 minutes. If vacuum drops, there is a leak that must be found and corrected before proceeding.
    ⚠Inadequate vacuum time will leave moisture in the system which can damage the compressor
14. 14

    Recharge AC system
    Following your AC machine instructions, recharge the system with the correct amount of R-134a refrigerant (approximately 18 oz total system capacity, minus any remaining from recovery). Add fresh PAG oil as needed to replace what was lost with the old hose (typically 1-2 oz total).
15. 15

    Test AC operation
    Start the engine and turn on the AC to maximum cold with fan on high. Allow the system to run for 5 minutes. Verify the compressor engages, both AC lines show appropriate temperature differential (high side warm, low side cold), and cold air blows from vents. Check all new connections for signs of oil or refrigerant leaks.

Reassembly

1. Reinstall engine cover by aligning clips and pressing firmly until seated
2. Reinstall front undertray if removed, ensuring all clips and bolts are secure
3. Clean any spilled refrigerant oil from engine bay surfaces

Verification

• Verify cold air blows from all dashboard vents when AC is on maximum
• Check that AC compressor cycles on and off normally during operation
• Inspect all AC line connections for any signs of oil leakage after test drive
• Use AC leak detector or soap solution to verify no refrigerant leaks at new connections
• Verify AC system maintains proper pressure readings on both high and low sides
• Confirm no unusual noises from compressor or hissing sounds indicating leaks

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