This procedure adds the correct amount of PAG oil to the AC compressor to maintain proper lubrication after refrigerant loss or component replacement.

Warnings

Tools required

Parts

• AC line O-rings × 4 — Use OEM specification
• Shop towels × 1 — Generic

Fluids

• PAG 46 refrigerant oil — 0.25 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely if recently operated
3. Verify correct PAG oil type (PAG 46 for R-134a systems on 3.5L EcoBoost)
4. Determine correct oil quantity: If replacing compressor add 3 oz; if replacing condenser add 1 oz; if adding oil due to leak repair add only amount lost (typically 1-2 oz)
5. Ensure refrigerant recovery machine is properly connected and functioning
6. Locate AC service ports on driver's side of engine bay near firewall

Procedure

1. 1

   Recover refrigerant from system
   Connect refrigerant recovery machine to both low and high side service ports. Follow recovery machine instructions to fully evacuate all R-134a refrigerant from the system. Wait until machine indicates recovery is complete and system pressure reads 0 PSI on both gauges.
   ⚠️Never vent refrigerant to atmosphere - it is illegal and environmentally harmful.
2. 2

   Disconnect AC line fitting
   Locate the AC line connection at the compressor on the passenger side of the engine near the top. Use appropriate wrench to loosen and remove the high-side AC line fitting from the compressor. Cap the opening immediately to prevent moisture and debris entry. Remove and discard old O-rings from the fitting.
   ⚠Some residual refrigerant may remain - ensure area is well ventilated.
3. 3

   Measure and prepare PAG oil
   Using the oil injector tool, measure the exact amount of PAG 46 oil needed based on service performed. For oil top-up only, typically add 1-2 oz unless specific loss is known. Ensure oil is clean and free of contamination. If replacing compressor, pour oil directly into compressor inlet before installation.
4. 4

   Inject oil into system
   Connect the AC oil injector tool to the disconnected high-side AC line fitting or compressor port. Slowly inject the measured PAG oil into the system. If using the compressor port directly, rotate the compressor clutch hub by hand several times to distribute oil internally.
5. 5

   Install new O-rings
   Coat new O-rings lightly with fresh PAG oil. Install new O-rings onto the AC line fitting, ensuring they seat properly in their grooves. Inspect fitting threads for damage or debris and clean if necessary.
6. 6

   Reconnect AC line
   Thread the AC line fitting back onto the compressor by hand until snug, ensuring proper alignment to avoid cross-threading. Use torque wrench to tighten the AC line fitting to specification.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
7. 7

   Evacuate the system
   Connect vacuum pump to AC service ports through manifold gauge set. Run vacuum pump for minimum 30 minutes to achieve at least 29 inches of vacuum. Close valves and observe vacuum hold for 15 minutes - if vacuum drops, there is a leak that must be repaired before proceeding.
   ⚠Proper evacuation removes moisture which can freeze and damage AC components.
8. 8

   Recharge refrigerant
   With engine off, connect refrigerant charging equipment to low-side service port. Add R-134a refrigerant to system per manufacturer specification (typically 1.75-2.0 lbs for 3.5L EcoBoost). Monitor gauges and add refrigerant slowly. Final charge should be verified by weight or gauge pressures.

Reassembly

1. Verify all AC line connections are tight and properly torqued
2. Ensure no tools or shop towels are left in engine bay
3. Double-check that service port caps are reinstalled on both high and low side ports

Verification

• Start engine and turn AC to maximum cold setting with blower on high
• Allow system to run for 5 minutes and verify cold air from vents (typically 40-50°F)
• Check AC gauge pressures: Low side should read 25-45 PSI, high side 200-250 PSI at idle (values vary with ambient temperature)
• Inspect all AC line connections for signs of oil leaks or refrigerant seepage
• Listen for unusual compressor noises which could indicate incorrect oil level
• Verify AC clutch engages and disengages properly when AC is cycled on/off

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