AC Hose - Low Side

This procedure covers the removal and replacement of the low-side AC hose on a 2018-2024 Honda Accord with the 1.5L turbo engine, including refrigerant recovery, hose replacement, and system recharge.

Warnings

Tools required

Parts

• AC low-side hose assembly × 1 — Use OEM specification
• AC line O-rings × 4 — Use OEM specification
• R-134a refrigerant × 1 — Approximately 16 oz
• PAG oil (ND-11) × 1 — Honda ND-11 or equivalent

Preparation

1. Ensure engine is cold and vehicle is parked on level ground
2. Disconnect negative battery terminal and wait 3 minutes for airbag system to discharge
3. Remove engine cover by pulling upward on all four corners
4. Place drip pan under AC compressor area to catch any residual oil
5. Verify AC system pressure is normal before recovery (should show approximately 60-80 psi static pressure at 70°F ambient)

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to both high and low-side service ports. Follow recovery machine instructions to fully recover all R-134a refrigerant from the system. Document the amount recovered for comparison during recharge. Ensure recovery is complete (gauges reading vacuum or zero pressure).
2. 2

   Access low-side hose at evaporator connection
   Remove the passenger side lower dashboard panel by releasing three clips along the bottom edge and one screw near the kick panel. The evaporator outlet connection is visible behind the panel near the blower motor housing. Clean the area around the connection fitting to prevent contamination.
3. 3

   Disconnect evaporator end of low-side hose
   Using a 12mm wrench, loosen the AC line fitting at the evaporator outlet. Support the evaporator line with one hand while breaking the connection. Once loose, unthread by hand and carefully separate. Immediately cap both openings to prevent moisture and debris entry. Remove and discard old O-rings from the evaporator fitting.
   ⚠Residual refrigerant oil may drip from fittings. Have shop towels ready.
4. 4

   Remove low-side hose mounting bracket
   Locate the hose mounting bracket on the passenger side of the engine bay near the firewall. Remove the single 10mm bolt securing the hose bracket to the body. This allows the hose to be maneuvered for removal.
   Torque spec

   Mounting Bolts26 Nm (19 lb-ft)
5. 5

   Access compressor suction port
   From the top of the engine bay, locate the AC compressor on the front lower passenger side of the engine. The low-side hose connects to the larger suction port on top of the compressor. Clean around the fitting thoroughly.
6. 6

   Disconnect compressor end of low-side hose
   Using a 12mm wrench, loosen the AC line fitting at the compressor suction port. Once loose, unthread by hand and separate the connection. Cap the compressor port immediately. Remove and discard the old O-rings from both the hose and compressor fittings.
7. 7

   Remove low-side hose assembly
   Trace the hose routing from evaporator to compressor, releasing any additional clips or guides. Carefully maneuver the hose assembly out through the engine bay, avoiding contact with sharp edges or hot surfaces. Inspect the old hose for signs of damage, abrasion, or oil leakage.
8. 8

   Prepare new low-side hose
   Unpack new low-side hose and verify correct part number and routing configuration. Lubricate new O-rings with a thin coat of ND-11 PAG oil. Install new O-rings into both ends of the new hose assembly, ensuring they seat properly in their grooves without twisting or pinching.
   ℹ️Use only ND-11 PAG oil specified for Honda AC systems. Do not use incorrect PAG viscosity or substitute lubricants.
9. 9

   Install new hose to compressor
   Route the new low-side hose through the engine bay following the original path. Connect the hose to the compressor suction port, hand-threading the fitting until snug. Ensure O-rings remain properly seated. Using a torque wrench and 12mm wrench, tighten the AC line fitting to specification.
   Torque spec

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

    Install hose mounting bracket
    Position the hose into its mounting bracket on the firewall. Install the 10mm mounting bolt and torque to specification to secure the hose in its proper routing position.
    Torque spec

    Mounting Bolts26 Nm (19 lb-ft)
11. 11

    Connect hose to evaporator
    From inside the vehicle, guide the evaporator end of the hose to the evaporator outlet fitting. Hand-thread the connection until snug, verifying O-rings are properly seated. Using a torque wrench and 12mm wrench, tighten the AC line fitting to specification.
    Torque spec

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

    Vacuum and leak test system
    Connect AC vacuum pump to service ports. Pull vacuum on the system to 29+ inches Hg for a minimum of 45 minutes. Close valves and monitor vacuum for 15 minutes; pressure should remain stable indicating no leaks. If vacuum drops, locate and repair leak before proceeding.
    ⚠Inadequate vacuum time or failure to hold vacuum indicates moisture or leaks that will cause system failure.
13. 13

    Recharge AC system
    Using AC manifold gauges and refrigerant recovery/recharge machine, charge the system with the documented amount of R-134a recovered (typically 14-18 oz total system capacity). Add 2 oz of ND-11 PAG oil to compensate for oil lost with old hose. Monitor low-side pressure during charging; should stabilize around 25-35 psi with engine off at 70°F ambient.
14. 14

    Reinstall interior and engine components
    Reinstall the passenger side lower dashboard panel, ensuring all clips engage properly. Reinstall engine cover by aligning grommets and pressing down firmly at all four corners. Reconnect negative battery terminal.

Reassembly

1. Verify all AC line fittings are torqued to specification and connections are secure
2. Ensure hose routing does not contact moving parts, sharp edges, or exhaust components
3. Confirm all interior panels and trim pieces are properly secured
4. Double-check that engine cover is fully seated on all mounting grommets

Verification

• Start engine and turn AC to maximum cold with fan on high speed
• Allow system to run for 5 minutes and verify cold air from vents (should reach 40-50°F)
• Check low-side pressure with engine running at idle: should be 25-40 psi at 70°F ambient
• Check high-side pressure: should be 180-250 psi at 70°F ambient depending on humidity
• Inspect all AC line connections for signs of oil leakage indicating seal failure
• Listen for unusual noises from compressor or hissing sounds indicating leaks
• Verify blower motor operates normally at all speeds
• Test AC performance during short road test to confirm proper cooling under load

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