AC Orifice Tube

This procedure covers the replacement of the AC orifice tube on a 2015-2020 Ford F-150 with the 3.5L EcoBoost engine, including refrigerant recovery, line removal, orifice tube extraction, and system recharge.

Warnings

Tools required

Parts

• AC orifice tube × 1 — Use OEM specification
• AC line O-ring kit (various sizes) × 1 — Use OEM specification
• PAG 46 refrigerant oil × 1 — Motorcraft PAG 46
• R-134a refrigerant × 1 — As needed per system capacity

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine and AC system to cool completely (minimum 2 hours)
3. Ensure AC recovery machine is properly calibrated and oil separator tank is empty
4. Identify the liquid line (high pressure line from condenser to evaporator) on passenger side of engine bay
5. Verify you have correct replacement orifice tube and new O-rings before beginning

Procedure

1. 1

   Recover refrigerant from AC system
   Connect AC recovery machine to vehicle service ports. Follow machine manufacturer instructions to fully recover all refrigerant from the system. Record the amount recovered for recharge reference. Allow system to stabilize and verify complete recovery before proceeding.
   ⚠️Ensure recovery machine is properly connected before opening service valves to prevent refrigerant release.
2. 2

   Locate and access the orifice tube
   The orifice tube is located in the liquid line between the condenser and evaporator. On the 3.5L EcoBoost, access the liquid line on the passenger side of the engine bay near the firewall. The orifice tube is typically installed in the line just before it enters the evaporator inlet. Identify the inlet fitting with the larger diameter and slight bulge indicating orifice tube location.
3. 3

   Disconnect liquid line at evaporator inlet
   Locate the spring lock coupling at the evaporator inlet where the orifice tube is housed. Select the correct size spring lock disconnect tool. Insert the tool into the coupling and push firmly toward the garter spring while pulling the line away from the evaporator. Once disconnected, immediately cap the evaporator port with a clean cap or plug to prevent moisture entry.
   ⚠Residual refrigerant or oil may drip from disconnected lines. Have shop towels ready and wear gloves.
4. 4

   Remove old orifice tube
   Inspect the liquid line inlet opening to locate the orifice tube (small brass or plastic component with fine mesh screen). Insert the orifice tube puller tool into the line and carefully engage the tube body or internal ears. Apply steady pulling force while slightly rotating the tool. If the tube is stuck or breaks, use appropriate extraction tool to remove remaining pieces. Inspect removed tube for metal debris or blockage indicating compressor failure.
   ⚠If orifice tube contains excessive metal debris, compressor may be failing. Inspect entire system before reassembly.
5. 5

   Clean line and inspect components
   Use shop towels to clean the liquid line opening where the orifice tube was installed. Inspect the line bore for debris, corrosion, or damage. Check the condition of the O-rings in the spring lock coupling. Remove and discard old O-rings using a pick or small screwdriver. Inspect evaporator inlet port for damage.
6. 6

   Install new orifice tube
   Remove new orifice tube from sealed packaging. Note the orientation of the orifice tube - the inlet side (with larger screen) must face toward the condenser, not the evaporator. Apply a small amount of clean PAG 46 oil to the O-rings on the new orifice tube. Insert the tube into the liquid line by hand, ensuring it seats fully against the internal stop. The tube should insert smoothly without force.
   ⚠Installing orifice tube backward will severely restrict refrigerant flow and cause system failure. Verify correct orientation before installation.
7. 7

   Install new O-rings on spring lock coupling
   Select the correct size O-rings from the kit for the liquid line spring lock coupling. Lightly lubricate new O-rings with clean PAG 46 oil. Install new O-rings into the grooves on both the male and female sides of the spring lock coupling. Ensure O-rings are properly seated in their grooves without twists or damage.
8. 8

   Reconnect liquid line to evaporator
   Remove cap from evaporator inlet port. Verify both coupling halves are clean and O-rings are properly positioned. Align the liquid line with the evaporator inlet and push firmly until you hear and feel a distinct click indicating the garter spring has engaged. Pull back on the line to verify it is locked - it should not separate with moderate force.
   ⚠Incomplete coupling connection will leak refrigerant. Ensure positive engagement before proceeding.
9. 9

   Add refrigerant oil to system
   Based on the amount of oil expelled during recovery and service, add the appropriate amount of fresh PAG 46 oil to the system. Typical replacement is 1-2 ounces through the low-side service port. Consult service manual for exact oil balance procedures if significant oil was lost.
10. 10

    Evacuate AC system
    Connect evacuation equipment to both high and low service ports. Evacuate the system to at least 29 inches of vacuum (98 kPa) for a minimum of 30 minutes. After evacuation, close valves and monitor vacuum gauge for 10 minutes. Vacuum should hold steady, indicating no leaks. If vacuum drops significantly, locate and repair leak before proceeding.
11. 11

    Recharge AC system
    Using AC service machine or manifold gauge set, charge the system with R-134a refrigerant to the specified capacity (found on underhood label, typically 1.75-2.10 lbs for F-150). Charge slowly through the low-side port with engine running and AC set to maximum cold, recirculation mode, and blower on high. Monitor pressures throughout charging process.
    ⚠Overcharging the system can damage the compressor. Use accurate scales and follow capacity specifications exactly.
12. 12

    Verify system operation and check for leaks
    With engine running and AC on maximum, verify compressor engages and disengages normally. Check vent temperatures - should achieve approximately 40-50°F at center vents in ambient conditions. Use electronic leak detector to check all service connections, particularly the spring lock coupling at the evaporator inlet. Monitor system pressures to verify they are within normal operating range.

Reassembly

1. Ensure all service port caps are reinstalled and tightened
2. Verify spring lock coupling is fully engaged and not leaking
3. Check that no tools or parts were left in engine bay
4. Clean any spilled refrigerant oil from components

Verification

• Start engine and run AC system for 10 minutes at maximum cooling
• Verify center vent temperature is 40-50°F in ambient conditions around 70-80°F
• Confirm compressor clutch engages and disengages smoothly without noise
• Check that low-side pressure is approximately 25-35 PSI and high-side is 150-250 PSI at idle (varies with ambient temperature)
• Use leak detector to verify no refrigerant leaks at spring lock coupling or service ports
• Listen for unusual noises from compressor or expansion sounds indicating restriction
• Test drive vehicle and verify AC performance under load conditions

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