Cooling Fan Relay

This procedure covers the location, removal, and replacement of the cooling fan relay in the engine compartment relay/fuse box on a 2015-2020 Ford F-150 with the 3.5L EcoBoost V6 engine.

Warnings

Tools required

Parts

• Cooling fan relay × 1 — Ford OEM relay or equivalent (verify amperage rating)

Preparation

1. Park vehicle on level surface and turn off engine
2. Allow engine to cool for at least 30 minutes if recently operated
3. Open hood and secure with prop rod
4. Locate the engine compartment fuse/relay box on the driver's side of the engine bay near the firewall

Procedure

1. 1

   Remove fuse box cover
   Press the release tabs on both sides of the engine compartment fuse box cover and lift upward to remove. The cover may have a diagram showing relay positions on the underside.
2. 2

   Identify cooling fan relay
   Locate the cooling fan relay using the diagram on the fuse box cover or owner's manual. On 2015-2017 models, it is typically in position F1.19 (a large square relay). On 2018-2020 models, verify the exact position as Ford relocated some relays. The cooling fan relay is typically a 40-50 amp mini ISO relay.
3. 3

   Test existing relay (optional)
   If diagnosing a cooling fan issue, you can test the existing relay before removal using a multimeter to check for continuity and proper switching. With ignition on and engine at operating temperature, the relay should click and show continuity when the cooling fan activates.
4. 4

   Remove cooling fan relay
   Firmly grasp the relay body and pull straight upward with steady pressure to extract it from the socket. The relay has friction-fit terminals and may require moderate force. Avoid rocking side to side as this can damage the socket terminals. If stuck, use needle-nose pliers to grip the relay body carefully.
5. 5

   Inspect relay socket
   Examine the relay socket for corrosion, bent pins, or debris. Check that all four terminal contacts are clean and properly aligned. If corrosion is present, clean terminals with electrical contact cleaner and allow to dry completely before proceeding.
6. 6

   Install new cooling fan relay
   Align the new relay with the socket, ensuring proper orientation by matching the tab or notch on the relay base with the corresponding feature in the socket. Push the relay firmly into place until it seats completely and is flush with surrounding relays. You should feel it click into position.
7. 7

   Reinstall fuse box cover
   Position the fuse box cover over the fuse box and press down firmly on all edges until the clips engage and the cover is secure. Ensure no wiring is pinched beneath the cover.

Reassembly

1. Ensure fuse box cover is fully seated and latched on all sides
2. Verify no tools or parts are left in the engine compartment

Verification

• Start the engine and allow it to reach normal operating temperature (typically 195-220°F)
• The cooling fan should activate automatically when coolant temperature reaches the programmed threshold (usually around 230°F)
• Listen for the relay click when the fan engages, and verify the fan spins
• Turn on the air conditioning system; the cooling fan should activate immediately with A/C compressor engagement
• If fan does not operate, verify relay is fully seated and recheck relay position against diagram
• Use a scan tool to command cooling fan operation if available to verify proper relay function

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