This procedure replaces the AC high pressure switch on a 2015-2020 Ford F-150 with 3.5L EcoBoost V6 engine. The switch monitors refrigerant pressure and must be replaced when faulty to restore proper AC system operation.

Warnings

Tools required

Parts

• AC high pressure switch × 1 — Use OEM specification
• AC line O-rings × 2 — Use OEM specification
• PAG oil (refrigerant oil) × 1 — ND-12 PAG 46

Fluids

• R-134a refrigerant

Preparation

1. Ensure engine is completely cool before beginning work
2. Park vehicle on level surface and engage parking brake
3. Open hood and secure with prop rod
4. Verify AC system refrigerant type matches vehicle specification (R-134a)
5. Have AC recovery equipment ready and operational

Procedure

1. 1

   Recover AC refrigerant
   Connect AC recovery machine to service ports on AC lines. Follow machine manufacturer instructions to fully recover all refrigerant from the system. Ensure recovery is complete before proceeding. Record amount of refrigerant recovered for recharge reference.
2. 2

   Locate AC high pressure switch
   The AC high pressure switch is located on the high-pressure AC line near the condenser on the driver side of the engine bay. It is a small electrical switch with a single connector threaded into the AC line. Trace the high-pressure line from the compressor to locate the switch.
3. 3

   Disconnect electrical connector
   Press the locking tab on the electrical connector and pull straight away from the AC high pressure switch. Do not pull on wires. Set connector aside where it will not contact hot or moving components.
4. 4

   Remove AC high pressure switch
   Using an appropriate wrench, carefully unthread the AC high pressure switch from the high-pressure line. Turn counterclockwise to remove. Be prepared for a small amount of residual refrigerant oil to leak out. Keep clean shop towels ready to catch any oil drips.
5. 5

   Inspect and clean fitting
   Inspect the threads on the AC line fitting for damage or debris. Clean threads with a lint-free shop towel. Check the O-ring sealing surface for scratches or corrosion. Minor surface imperfections can be cleaned, but deep scratches require line replacement.
6. 6

   Install new O-ring
   Remove the old O-ring from the switch port if still present. Install new O-ring onto the new AC high pressure switch. Coat O-ring lightly with fresh PAG oil (ND-12 PAG 46) to ensure proper seal and prevent damage during installation.
7. 7

   Install new AC high pressure switch
   Thread the new AC high pressure switch into the high-pressure line by hand first to ensure threads engage properly. Once hand-tight, use a torque wrench and appropriate socket to tighten to specification. Do not over-tighten as this can damage the fitting or O-ring.
   Torque spec

   AC Line Fittings20 Nm (15 lb-ft)
8. 8

   Reconnect electrical connector
   Push the electrical connector firmly onto the new AC high pressure switch until the locking tab clicks into place. Gently tug on the connector to verify it is fully seated and locked.
9. 9

   Evacuate AC system
   Connect vacuum pump to AC system service ports. Evacuate system to at least 29 inches of mercury (Hg) vacuum. Maintain vacuum for minimum 30 minutes to remove all moisture and air from the system. Monitor vacuum gauge to ensure system holds vacuum without loss, indicating no leaks.
10. 10

    Recharge AC system
    Using AC manifold gauges and refrigerant equipment, recharge system with the amount of R-134a refrigerant recovered in Step 1, plus any oil lost during repair (typically 1-2 oz PAG oil). Follow proper charging procedure: add refrigerant through low-side port only with engine running and AC on maximum cold.

Reassembly

1. Double-check all AC line fittings are tight and electrical connector is fully seated
2. Verify no tools or shop towels remain in engine compartment
3. Close hood after verifying repair is complete

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 is produced
• Use AC manifold gauges to verify proper high and low side pressures (high side should be 200-250 psi, low side 25-40 psi at idle with ambient temperature 70-80°F)
• Inspect AC high pressure switch area for refrigerant leaks using electronic leak detector or soap solution
• Verify AC compressor cycles on and off properly as controlled by high pressure switch
• Check for unusual noises from compressor or AC system components
• Test AC performance under various blower speeds and temperature settings

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