AC Expansion Valve (TXV)

This procedure replaces the AC expansion valve (TXV) on a 2014-2018 Chevrolet Silverado 1500 with the 5.3L V8 engine, requiring full refrigerant recovery, evaporator access, and system recharge.

Warnings

Tools required

Parts

• AC Expansion Valve (TXV) × 1 — Use OEM specification
• AC system O-ring kit × 1 — Contains various sizes for AC fittings
• R-134a refrigerant × 1 — Approximately 2.0 lbs
• PAG oil (ND-12 or equivalent) × 1 — For AC system, 2-4 oz

Preparation

1. Park vehicle on level ground and engage parking brake
2. Disconnect negative battery cable and wait 2 minutes for airbag system discharge
3. Verify AC system has not been previously contaminated or shows signs of compressor failure
4. Connect AC recovery machine and fully recover all refrigerant from the system per EPA guidelines
5. Record the amount of oil recovered for replacement calculation
6. Remove lower dash panel trim on passenger side
7. Move passenger seat fully rearward for working clearance

Procedure

1. 1

   Remove glove box assembly
   Open glove box and remove contents. Squeeze sides inward to release stop tabs and lower glove box completely. Remove screws securing glove box hinge pins and remove entire glove box assembly from dashboard.
2. 2

   Disconnect blower motor
   Locate blower motor on passenger side of HVAC case. Disconnect electrical connector from blower motor. Remove blower motor mounting screws and carefully remove blower motor assembly from HVAC case. Set aside in clean area.
   Torque spec

   Blower Motor Screws8 Nm (6 lb-ft)
3. 3

   Remove HVAC case covers
   Locate and remove all cover screws on the HVAC case accessible from the passenger side. This includes the thermal expansion valve access cover. Carefully pry covers away from case using trim tools to avoid cracking plastic. Note position of any foam seals.
   ⚠HVAC case covers are brittle on older vehicles. Work carefully to avoid breaking mounting tabs.
   Torque spec

   Cover Screws14 Nm (10 lb-ft)
4. 4

   Access expansion valve connections
   With the TXV access cover removed, identify the expansion valve body mounted to the evaporator. It will have two refrigerant line connections (inlet from liquid line and outlet to evaporator). Take photos for reassembly reference showing line routing and orientation.
5. 5

   Disconnect refrigerant lines from expansion valve
   Using appropriate wrench, carefully loosen and remove the refrigerant line fittings from the expansion valve. Support the valve body to prevent stress on evaporator connections. Remove and discard old O-rings from both lines. Immediately cap all open fittings to prevent moisture intrusion.
   ⚠Even after recovery, residual refrigerant may remain. Work in well-ventilated area and wear eye protection.
6. 6

   Remove expansion valve from evaporator
   Remove mounting bolts or clips securing expansion valve to the evaporator inlet/outlet tubes. Carefully extract expansion valve from evaporator connections. Note orientation of sensing bulb if equipped. Remove and discard O-rings from evaporator connections. Cap evaporator openings immediately.
   ⚠Do not allow debris to enter evaporator or refrigerant lines. Keep all openings capped when not actively working on them.
   Torque spec

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

   Prepare new expansion valve
   Unpack new expansion valve and verify it matches old unit exactly. Install new O-rings on evaporator connection points and on valve body connections. Lightly coat all new O-rings with clean PAG oil (ND-12). Do not reuse old O-rings. Verify sensing bulb is properly positioned if applicable.
8. 8

   Install expansion valve to evaporator
   Remove caps from evaporator connections. Carefully align new expansion valve with evaporator inlet and outlet tubes, ensuring proper orientation per photos taken during removal. Install and hand-tighten mounting hardware. Torque expansion valve mounting bolts to specification in proper sequence.
   ℹ️Expansion valve must be oriented correctly for proper refrigerant flow direction. Inlet comes from liquid line, outlet goes to evaporator.
   Torque spec

   Expansion Valve10 Nm (7 lb-ft)
9. 9

   Reconnect refrigerant lines
   Remove caps from refrigerant lines. Install new O-rings on line fittings and coat with PAG oil. Connect liquid line to expansion valve inlet and evaporator outlet line to valve outlet. Hand-tighten fittings, then torque to specification using backup wrench to prevent valve body rotation.
   ⚠Cross-threading aluminum AC fittings will require expensive line replacement. Start all threads by hand and verify smooth rotation before using wrenches.
   Torque spec

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

    Reinstall HVAC case covers and blower motor
    Reinstall all HVAC case covers with foam seals in original positions. Torque cover screws to specification. Reinstall blower motor assembly, ensuring it seats fully in case opening. Torque blower motor screws to specification and reconnect electrical connector.
    Torque spec

    Cover Screws14 Nm (10 lb-ft)

    Blower Motor Screws8 Nm (6 lb-ft)
11. 11

    Reinstall glove box and interior trim
    Reinstall glove box assembly by aligning hinge pins and securing with screws. Verify glove box opens and closes smoothly with stop tabs functioning. Reinstall lower dash trim panels removed during preparation.
12. 12

    Evacuate AC system
    Reconnect negative battery cable. Connect vacuum pump to AC system service ports. Evacuate system to 29+ inches Hg vacuum for minimum 45 minutes. Monitor for vacuum decay - system should hold vacuum for 15 minutes after pump shutoff. Any vacuum loss indicates a leak that must be repaired.
    ⚠Proper evacuation removes moisture that would freeze at the expansion valve and damage the compressor. Do not skip or shorten evacuation time.
13. 13

    Recharge AC system
    With system still under vacuum, add calculated amount of PAG oil based on oil recovered plus 2 oz for new valve. Charge system with R-134a refrigerant to specification listed on underhood label (typically 1.75-2.25 lbs). Use manifold gauges to monitor pressures during charging. Charge through low-side port only with engine off, then run engine at 1500 RPM to complete charging.
    ⚠Overcharging reduces cooling efficiency and can damage compressor. Use precise charging equipment and follow underhood label specifications exactly.
14. 14

    Leak test AC system
    With system charged and stabilized, use electronic leak detector to check all connections made during this repair, especially expansion valve fittings and evaporator connections. Check with engine running and AC on MAX. Any detected leaks must be corrected by recovering refrigerant, repairing leak, and repeating evacuation/recharge process.

Reassembly

1. Verify all interior trim panels are securely reinstalled and clips fully engaged
2. Ensure blower motor electrical connector is fully seated and locked
3. Check that glove box operates smoothly without interference
4. Verify no tools or parts were left in HVAC case or dashboard area

Verification

• Start engine and turn AC to MAX cold with fan on high
• Verify compressor clutch engages and remains engaged
• Check that center vent air temperature reaches 38-42°F within 5 minutes of operation at idle
• Monitor manifold gauge pressures: Low side should be 25-35 PSI, high side 200-250 PSI at 75°F ambient with engine at 1500 RPM
• Verify no unusual noises from HVAC case or compressor
• Check for proper airflow from all vents with no restrictions
• Confirm no refrigerant odor in cabin indicating leak at evaporator area
• Test drive vehicle and verify AC maintains cold temperature under load
• Recheck all accessible fittings with leak detector after system has cycled several times

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