AC Orifice Tube

Replace the AC orifice tube, a component that filters and meters refrigerant flow to prevent contamination and ensure proper cooling system operation.

Warnings

Tools required

Parts

• AC orifice tube × 1 — Use OEM specification
• AC line O-rings × 4 — Use OEM specification
• R-134a refrigerant × 1 — As needed per system capacity
• PAG 46 compressor oil × 1 — Motorcraft PAG oil

Fluids

• PAG 46 AC compressor oil — 0.25 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine and AC system to cool completely (minimum 2 hours)
3. Disconnect negative battery terminal to prevent accidental compressor engagement
4. Connect AC recovery machine and fully recover all refrigerant from system following EPA guidelines
5. Document amount of oil and refrigerant recovered for recharge reference
6. Clean the work area around AC lines to prevent contamination

Procedure

1. 1

   Locate the orifice tube
   The orifice tube is located in the liquid line between the condenser and evaporator, typically at the evaporator inlet near the firewall on the passenger side. Identify the liquid line connection point - it will be the smaller diameter line compared to the suction line. The orifice tube housing has a distinctive crimped section or bulge in the line.
2. 2

   Disconnect the liquid line fitting
   Using the appropriate line wrench, carefully loosen and disconnect the liquid line fitting at the evaporator inlet where the orifice tube is located. Use a backup wrench on the stationary fitting to prevent line twist. Cap both open ends immediately with plugs or clean shop towels to prevent contamination and moisture entry.
   ⚠Even after recovery, residual refrigerant may be present. Allow any remaining pressure to vent slowly before fully removing fittings.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
3. 3

   Inspect and remove old O-rings
   Remove and discard the old O-rings from both sides of the disconnected fitting. Inspect the sealing surfaces for damage, scoring, or corrosion. Clean the fitting surfaces thoroughly with a lint-free cloth. Any debris left behind can cause system contamination.
4. 4

   Extract the orifice tube
   Insert the orifice tube removal tool into the liquid line opening. The tool will grip the tabs or body of the orifice tube. Carefully twist and pull to extract the tube from the line. If the tube is stuck due to debris buildup, work it gently back and forth while pulling. Avoid breaking the tube inside the line as this will require more extensive disassembly.
   ⚠If the orifice tube breaks during removal, all fragments must be retrieved. A broken tube left in the system will cause blockage and compressor damage.
5. 5

   Inspect the removed orifice tube
   Examine the removed orifice tube screen for metal particles, debris, or excessive contamination. Heavy metal debris indicates compressor or other component failure requiring additional system service. Note the condition and amount of debris for diagnosis. Check if the tube O-rings are intact.
6. 6

   Clean the liquid line
   Using compressed air (if available) and clean shop towels, carefully clean the inside of the liquid line where the orifice tube seats. Ensure no debris or old O-ring material remains. The seating area must be completely clean for proper seal.
7. 7

   Prepare the new orifice tube
   Remove the new orifice tube from packaging. Lightly coat the O-rings on the new orifice tube with clean PAG oil (same viscosity as system oil). Verify the tube is the correct replacement by comparing screen mesh size and overall dimensions to the old tube. Ensure the screen is clean and free of any manufacturing debris.
8. 8

   Install the new orifice tube
   Carefully insert the new orifice tube into the liquid line opening, ensuring correct orientation. The tube should seat firmly against its stop. The inlet side (typically marked with an arrow or facing the condenser) must face the correct direction for refrigerant flow. Push firmly until fully seated - you should feel it bottom out.
9. 9

   Install new O-rings on line fittings
   Install new O-rings on both the male and female sides of the AC line fittings. Lightly coat each new O-ring with clean PAG oil. Ensure O-rings are seated properly in their grooves without twisting or pinching. Do not reuse old O-rings as they lose their sealing ability once compressed.
   ℹ️Use only AC-specific O-rings. Standard O-rings will deteriorate when exposed to refrigerant and PAG oil.
10. 10

    Reconnect the liquid line
    Carefully align and hand-thread the liquid line fitting to avoid cross-threading. Thread the fitting by hand until snug to ensure proper alignment. Use a torque wrench and line wrench to tighten the fitting to specification. Hold the stationary fitting with a backup wrench to prevent line twist.
    Torque spec

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

    Add replacement PAG oil
    Add the appropriate amount of fresh PAG oil to the system to replace oil lost during recovery and trapped in the old orifice tube. Typically add 1-2 ounces through the low-side service port or as specified by the amount recovered. Use only Motorcraft PAG oil or equivalent specified for R-134a systems.
12. 12

    Evacuate the AC system
    Connect the AC recovery/evacuation machine to both service ports. Evacuate the system to pull a deep vacuum (minimum 29 inches Hg) for at least 30-45 minutes. Monitor for vacuum decay - the system should hold vacuum without dropping, indicating no leaks. If vacuum drops, locate and repair the leak before proceeding.
13. 13

    Recharge the AC system
    Using the AC machine, recharge the system with the correct amount of R-134a refrigerant as documented during recovery or per system capacity specifications (typically found on the underhood label). Do not overcharge. Add UV dye if desired for future leak detection. Monitor pressures during recharge to ensure proper fill.
14. 14

    Reconnect battery and test system
    Reconnect the negative battery terminal. Start the engine and turn on the AC system to maximum cooling. Allow the system to run for 5-10 minutes. Monitor system pressures using gauges - low side should be 25-45 PSI and high side 150-250 PSI at idle (values vary with ambient temperature). Verify cold air output from vents.

Reassembly

1. Verify all AC line fittings are properly torqued and show no signs of leakage
2. Ensure battery is securely reconnected with clean terminals
3. Double-check that no tools or materials were left in the engine compartment

Verification

• Run AC system at maximum cooling for 10-15 minutes and verify cold air output (typically 40-50°F at vent)
• Check system pressures with manifold gauges - both high and low side should be within specification for ambient temperature
• Inspect all connections for refrigerant leaks using electronic leak detector or soap solution
• Verify compressor cycles on and off normally without unusual noises
• Monitor system operation over next few days to ensure consistent cooling performance
• If UV dye was added, inspect connections with UV light for any signs of leakage after initial operation

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