Cooling Fan Relay

This procedure covers the diagnosis and replacement of the cooling fan relay in the 2018-2024 Honda Accord 1.5L Turbo, located in the under-hood fuse/relay box.

Warnings

Tools required

Parts

• Cooling fan relay × 1 — Honda 39794-SDA-A03 or equivalent

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn off engine and allow to cool completely (minimum 30 minutes)
3. Open hood and secure with prop rod
4. Disconnect negative battery terminal and wait 3 minutes before proceeding

Procedure

1. 1

   Locate under-hood fuse/relay box
   The under-hood fuse/relay box is located on the driver's side of the engine compartment, near the battery. It is a black rectangular box with a removable cover.
2. 2

   Remove fuse box cover
   Release the clips securing the fuse box cover by pressing or lifting them (depending on design). Carefully lift the cover straight up to remove it. The relay diagram is typically printed on the underside of the cover.
3. 3

   Identify cooling fan relay
   Refer to the relay diagram on the fuse box cover or in the owner's manual to identify the cooling fan relay location. On 2018-2024 Accord 1.5L models, it is typically labeled as 'RADIATOR FAN RELAY' or similar designation. Note the relay position and orientation before removal.
4. 4

   Test relay operation (optional diagnostic step)
   If diagnosing a fan issue, you can test the relay before replacement. With battery connected, turn ignition to ON position and allow engine to reach operating temperature (or use scan tool to command fan on). Listen for relay click and check for voltage at relay terminals with multimeter. Disconnect battery again before proceeding with removal.
5. 5

   Remove cooling fan relay
   Using a relay puller tool or needle-nose pliers, grasp the relay body firmly and pull straight upward with steady pressure. Do not rock side to side excessively as this may damage the relay socket pins. The relay should release from the socket with moderate force.
6. 6

   Inspect relay socket and terminals
   Examine the relay socket in the fuse box for corrosion, damage, or burned terminals. Check that all socket pins are straight and undamaged. If corrosion is present, clean terminals with electrical contact cleaner and a small brush. If terminals are burned or damaged, the entire fuse box may require replacement.
7. 7

   Install new cooling fan relay
   Verify the new relay matches the part number and pin configuration of the old relay. Align the relay pins with the socket, ensuring correct orientation (relay will only fit one way). Push the relay firmly into the socket until it seats completely and is flush with surrounding relays.
8. 8

   Reinstall fuse box cover
   Position the fuse box cover over the fuse/relay box, ensuring it is properly aligned. Press down firmly until all clips engage and the cover is fully seated.
9. 9

   Reconnect battery
   Reconnect the negative battery terminal and tighten the terminal bolt securely. Ensure the connection is clean and tight.

Reassembly

1. Verify fuse box cover is fully secured with all clips engaged
2. Ensure no tools or parts are left in engine compartment
3. Close hood securely

Verification

• Start the engine and allow it to idle
• Monitor engine temperature gauge until cooling fan activates (typically around 220°F / 104°C)
• Confirm cooling fan operates smoothly without unusual noises
• Verify fan cycles on and off appropriately as engine temperature fluctuates
• If fan does not operate, check fuse, fan motor, coolant temperature sensor, and wiring before concluding relay is faulty
• Use Honda Diagnostic System (HDS) or compatible scan tool to command cooling fan on/off to verify relay function if available

Related trouble codes on this vehicle

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