AC Expansion Valve (TXV)

Replace the AC expansion valve (TXV) on a 2018-2024 Honda Accord 1.5L Turbo, including refrigerant recovery, valve replacement, and system recharge.

Warnings

Tools required

Parts

• AC Expansion Valve (TXV) × 1 — Honda OEM 38740-RBC-004 or equivalent
• AC O-ring kit (assorted sizes for AC lines) × 1 — Use OEM specification
• PAG 46 refrigerant oil × 1 — Honda PN 38899-PYC-A01 or equivalent
• R-134a refrigerant × 1 — Approximately 20 oz

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely (minimum 1 hour)
3. Disconnect negative battery terminal and wait 3 minutes for SRS system to discharge
4. Verify AC system operation and note any existing issues before repair
5. Gather all required tools, parts, and refrigerant oil before beginning
6. Ensure AC recovery machine is properly calibrated and oil separator is clean

Procedure

1. 1

   Recover AC refrigerant
   Connect AC recovery machine to high and low side service ports. Follow machine manufacturer instructions to completely recover all refrigerant from the system. Record the amount of refrigerant and oil recovered for later reference. Verify system pressure reaches 0 psi on gauges.
2. 2

   Remove engine cover
   Remove the plastic engine cover by pulling upward firmly on the front edge to release the clips, then lift away. Set aside in a clean area.
   Torque spec

   Cover Screws10 Nm (8 lb-ft)
3. 3

   Access expansion valve area
   The expansion valve is located on the evaporator inlet line near the firewall on the passenger side. Remove the wiring harness clips and move any interfering harnesses aside. If needed, remove the intake air duct for better access by loosening the clamps and disconnecting the MAF sensor connector.
4. 4

   Disconnect liquid line from expansion valve
   Using a flare nut wrench, carefully loosen the liquid line fitting at the expansion valve inlet (smaller line from condenser). Once loose, use a regular wrench to remove completely. Immediately cap the open line with a clean plug to prevent moisture intrusion. Remove and discard the old O-ring.
5. 5

   Disconnect evaporator line from expansion valve
   Using a flare nut wrench, carefully loosen the evaporator inlet line fitting at the expansion valve outlet. Once loose, remove completely and immediately cap the open line. Remove and discard the old O-ring. Have shop towels ready as residual oil may drain from connections.
6. 6

   Remove expansion valve sensor bulb
   The TXV has a sensing bulb clamped to the evaporator outlet line. Carefully remove the clamp securing the bulb using needle nose pliers or appropriate tool. Gently separate the bulb from the line without kinking the capillary tube.
7. 7

   Remove expansion valve
   Remove the mounting bracket bolts securing the expansion valve assembly. Carefully extract the valve, taking care not to damage the capillary tube or bulb. Inspect the valve screen for debris or contamination. If excessive debris is present, the system may require flushing.
   Torque spec

   Expansion Valve10 Nm (7 lb-ft)
8. 8

   Prepare new expansion valve
   Remove new expansion valve from packaging only when ready to install. Verify the part number matches the original valve. Check that the valve screen is clean and the sensing bulb is undamaged. Add approximately 2-3 ml of fresh PAG 46 oil into the inlet port of the new valve.
9. 9

   Install new expansion valve
   Position the new expansion valve in the mounting bracket and secure with mounting bolts. Torque mounting bolts evenly to specification. Position the sensing bulb against the evaporator outlet line at the 6 o'clock position and secure the clamp firmly but not over-tightened.
   Torque spec

   Expansion Valve10 Nm (7 lb-ft)
10. 10

    Install new O-rings on liquid line
    Lubricate new O-rings with fresh PAG 46 oil and install onto the liquid line fitting. Ensure O-rings are properly seated in their grooves without twisting or pinching. Verify O-rings are the correct size and thickness for the connection.
11. 11

    Connect liquid line to expansion valve
    Remove the cap from the expansion valve inlet. Thread the liquid line fitting by hand until snug to ensure proper thread engagement. Using a flare nut wrench and backup wrench, tighten the fitting to specification. Do not over-tighten as this can damage the O-rings and cause leaks.
    Torque spec

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

    Install new O-rings on evaporator line
    Lubricate new O-rings with fresh PAG 46 oil and install onto the evaporator inlet line fitting. Ensure O-rings are properly seated without twisting. Add approximately 2 ml of PAG 46 oil into the open fitting before connection.
13. 13

    Connect evaporator line to expansion valve
    Remove the cap from the expansion valve outlet. Thread the evaporator line fitting by hand until snug. Using a flare nut wrench and backup wrench, tighten the fitting to specification. Verify the connection is secure and properly aligned.
    Torque spec

    AC Line Fittings20 Nm (15 lb-ft)
14. 14

    Reinstall removed components
    Reinstall any wiring harnesses, clips, and the intake air duct if removed. Reconnect the MAF sensor connector if disconnected. Ensure all components are properly secured and no wires are pinched or routed incorrectly. Reinstall the engine cover.
15. 15

    Evacuate AC system
    Connect the vacuum pump to the AC service ports via manifold gauges. Evacuate the system to a minimum of 29 inches Hg (750 mmHg) vacuum for at least 45 minutes. After evacuation, close valves and observe vacuum hold for 10 minutes. If vacuum drops more than 1 inch Hg, there is a leak that must be repaired.
16. 16

    Recharge AC system
    With the system under vacuum, charge with the correct amount of R-134a refrigerant per the underhood label (typically 18-20 oz for 1.5L Turbo). Add refrigerant oil to compensate for oil lost during recovery (typically 1-2 oz if minimal oil was lost). Reconnect negative battery terminal. Start the engine and verify AC system operation.

Reassembly

1. Verify all AC line fittings are torqued to specification and connections are secure
2. Ensure the expansion valve sensing bulb is properly positioned and clamped to the evaporator outlet line
3. Confirm all wiring harnesses and clips are reinstalled to original positions
4. Double-check that no tools or parts were left in the engine bay

Verification

• Start engine and set AC to MAX COLD with blower on HIGH
• Allow system to run for 5 minutes and monitor low side pressure (should be 25-35 psi) and high side pressure (should be 150-250 psi depending on ambient temperature)
• Verify vent temperature is 40-50°F colder than ambient temperature
• Inspect all AC line connections for signs of leaks using leak detector or soapy water
• Check that evaporator outlet line (return to compressor) is cold and sweating, indicating proper expansion valve operation
• Verify no abnormal noises from AC system components
• Test AC operation in various modes (MAX, Normal, different fan speeds) to ensure proper function
• Consider UV dye injection for long-term leak verification if desired

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