hvac

AC Low Pressure Switch

for 2017 Ford F-150 5.0L V8 Coyote · RWD

Difficulty

Moderate

Time

42 min

Tools

Steps

🤖AI-generated, not yet human-verified. This walkthrough was produced by AI and may contain errors. Treat it as a guide, cross-check every step and torque value against the manufacturer's service manual, and stop if anything looks unsafe. This is a moderate-risk job — take extra care.

This procedure covers the replacement of the AC low pressure switch on a 2015-2020 Ford F-150 with the 5.0L V8 Coyote engine, including refrigerant recovery, switch replacement, and system recharge.

Warnings

⚠️AC refrigerant must be properly recovered by certified equipment. Venting refrigerant to atmosphere is illegal and environmentally harmful.

⚠Wear safety glasses and gloves when working with AC system. Refrigerant can cause frostbite on contact with skin.

⚠AC system operates under high pressure. Never loosen fittings without first recovering refrigerant.

ℹ️This job requires EPA Section 609 certification to legally handle automotive refrigerant.

Tools required

AC refrigerant recovery machineEssential

Manifold gauge setEssential

Torque wrench (10-50 Nm range)Essential

Socket set (metric)

Wrench set (metric)

Ratchet and extensions

Refrigerant leak detector

PAG oil for AC systemEssential

Vacuum pumpEssential

Parts

AC low pressure switch × 1 — Use OEM Ford specification
AC system O-rings × 2 — Use OEM specification with proper seal type
R-134a refrigerant × 1 — Approximately 1.5-2.0 lbs

Preparation

Park vehicle on level surface and engage parking brake
Turn off engine and allow to cool if recently operated
Ensure AC system has been off for at least 10 minutes
Verify you have proper refrigerant recovery equipment and certification
Locate the low pressure switch on the AC suction line near the accumulator/dryer on passenger side of engine bay

Procedure

1
Recover AC refrigerant
Connect the AC recovery machine to the service ports on the F-150. Follow the recovery machine manufacturer's instructions to completely evacuate all R-134a refrigerant from the system. Record the amount of refrigerant and oil recovered for proper recharge quantities.
2
Disconnect battery negative terminal
Disconnect the negative battery cable to prevent electrical issues while working with the pressure switch wiring. Wait 2 minutes for electrical systems to discharge.
3
Access the low pressure switch
The low pressure switch is located on the larger diameter suction line between the evaporator outlet and compressor inlet, typically near the accumulator/dryer assembly on the passenger side. Remove any plastic covers or shields that may obstruct access to the switch.
4
Disconnect electrical connector
Press the locking tab on the electrical connector attached to the low pressure switch and pull the connector straight off. Inspect the connector terminals for corrosion or damage.
5
Remove old low pressure switch
Using an appropriate wrench, carefully unscrew the low pressure switch from the AC line port. The switch threads directly into the line. Remove the old O-ring seal from the port and inspect the sealing surface for damage or debris. Clean the port threads and sealing surface with a clean, lint-free cloth.
6
Install new O-ring and prepare switch
Install a new O-ring onto the new low pressure switch. Apply a small amount of fresh PAG oil (compatible with R-134a systems) to the O-ring to ensure proper sealing and prevent damage during installation. Do not over-oil as excess can contaminate the system.
7
Install new low pressure switch
Thread the new low pressure switch into the AC line port by hand until finger-tight. Use a torque wrench to tighten to the specified torque value. Do not over-tighten as this can damage the threads or crack the switch housing.
Torque spec
AC Line Fittings20 Nm (15 lb-ft)
8
Reconnect electrical connector
Push the electrical connector firmly onto the new low pressure switch until you hear or feel the locking tab click into place. Tug gently to verify it is secured.
9
Reconnect battery
Reconnect the negative battery cable and ensure it is secure.
10
Evacuate AC system
Connect a vacuum pump to the AC service ports. Evacuate the system to at least 29 inches of mercury (Hg) and hold vacuum for a minimum of 30 minutes to remove any moisture and air. Monitor for vacuum decay which would indicate a leak.
11
Recharge AC system
Using the manifold gauge set and refrigerant recovery/recharge machine, add the proper amount of R-134a refrigerant to the system (typically 1.5-2.0 lbs, verify exact capacity on the underhood label). Add PAG oil if significant oil was lost during recovery. Do not overcharge the system.

Reassembly

Reinstall any covers or shields that were removed for access
Verify all electrical connections are secure and properly routed
Ensure no tools or parts were left in the engine bay

Verification

Start the engine and turn AC to maximum cold with fan on high
Verify the AC compressor clutch engages (listen for click and observe clutch rotation)
Check for proper cold air output from vents within 2-3 minutes
Monitor AC system pressures with gauge set: low side should be 25-40 PSI and high side 150-250 PSI at idle (ambient temperature dependent)
Use refrigerant leak detector around the low pressure switch to verify no leaks
Check for proper operation of AC compressor cycling controlled by the pressure switch
Verify no warning lights or AC-related codes using a scan tool