AC Orifice Tube

Replace the AC orifice tube, a refrigerant metering device located in the liquid line between the condenser and evaporator, to restore proper AC cooling performance.

Warnings

Tools required

Parts

• AC orifice tube × 1 — Use OEM specification
• AC line O-rings × 4 — Use OEM specification
• R-134a refrigerant × 1 — Typically 18-22 oz - verify on underhood label
• PAG oil (for AC system) × 1 — Use OEM specification PAG 46

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn off engine and allow AC system to sit for at least 10 minutes
3. Verify AC compressor is not running
4. Locate the liquid line between condenser and evaporator - orifice tube is typically near the firewall in the liquid line inlet to evaporator
5. Have refrigerant recovery equipment ready and properly connected

Procedure

1. 1

   Recover AC refrigerant
   Connect AC recovery machine to system service ports. Follow machine instructions to fully recover all refrigerant from the system. Verify system is at 0 PSI before proceeding. Record amount of refrigerant and oil removed for proper recharge quantities.
2. 2

   Access orifice tube location
   Remove engine cover if equipped. Locate the liquid line connection near the firewall where it enters the evaporator. The orifice tube is inside the liquid line at this junction. Clean area around fittings to prevent contamination from entering system.
3. 3

   Disconnect liquid line fitting
   Using a line wrench to prevent rounding, carefully loosen and disconnect the liquid line fitting at the evaporator inlet. Expect residual refrigerant oil to drip out. Cap or plug open lines immediately to prevent moisture and contamination from entering the system.
   ⚠Small amounts of pressurized refrigerant may still be present. Allow any remaining pressure to dissipate slowly before fully removing fitting.
4. 4

   Extract old orifice tube
   The orifice tube is located inside the evaporator inlet pipe. Use an O-ring pick or orifice tube removal tool to carefully extract the tube assembly. Note the orientation - the shorter end with screen faces toward the evaporator. Inspect the old tube screen for debris or metal particles which indicate compressor damage.
   ℹ️If tube is stuck or breaks during removal, a special orifice tube extraction tool may be required. Do not damage the aluminum line bore.
5. 5

   Inspect system for contamination
   Examine the old orifice tube screen carefully. Metal particles indicate compressor failure and system requires flushing. Black debris suggests desiccant breakdown from accumulator. Clean debris indicates normal operation. If contamination is found, address root cause before proceeding.
6. 6

   Prepare new orifice tube
   Remove new orifice tube from packaging. Lightly coat the O-rings with fresh PAG oil (same viscosity as system requires, typically PAG 46). Verify the tube is the correct size and design for this application. Note the directional orientation markings.
7. 7

   Install new orifice tube
   Insert the new orifice tube into the evaporator inlet pipe with correct orientation - shorter screen end toward evaporator, longer dimpled end toward condenser. Push firmly until it seats completely against the internal stop. The tube should sit approximately 1 inch inside the pipe.
8. 8

   Replace O-rings and reconnect line
   Install new O-rings on the liquid line fitting, coating them with PAG oil. Add approximately 1-2 oz of fresh PAG oil into the open line to replace oil lost during service. Reconnect the liquid line fitting hand-tight first, then torque to specification using a line wrench.
   ⚠Use new O-rings only. Old O-rings will leak. Cross-threading aluminum fittings will destroy the line - thread carefully by hand first.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
9. 9

   Evacuate AC system
   Connect vacuum pump to AC service ports. Evacuate system to at least 29 inches of mercury vacuum for minimum 30 minutes, preferably 45 minutes. After evacuation, close valves and monitor vacuum gauge for 10 minutes - vacuum should hold steady indicating no leaks.
   ℹ️Proper evacuation removes moisture which can freeze at the orifice tube and cause AC failure. Do not skip or shorten evacuation time.
10. 10

    Recharge AC system
    Using refrigerant scale and manifold gauges, recharge system with correct amount of R-134a refrigerant as specified on underhood AC specification label (typically 18-22 oz for this vehicle). Charge through low-side port only with engine running and AC on MAX. Monitor pressures during charging.

Reassembly

1. Reinstall engine cover if removed
2. Verify all AC line connections are tight and properly torqued
3. Double-check that no tools or materials were left in engine bay

Verification

• Start engine and turn AC to MAX cooling with blower on high
• Check that compressor clutch engages and remains engaged
• Verify vent temperatures drop to 38-45°F within 5 minutes of operation
• Inspect all AC line connections for signs of refrigerant oil leaks
• Check low-side pressure (should be 25-35 PSI at idle, 80°F ambient) and high-side pressure (should be 175-225 PSI)
• Listen for abnormal AC compressor noises that might indicate remaining contamination
• Use electronic leak detector around all fittings to confirm no leaks
• Test AC performance during short road test to verify consistent operation

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