Upgrading from a mechanical clutch fan to a Spal electric fan conversion is one of the most effective cooling system modifications you can make on a Ford Mustang. Electric fans reduce parasitic drag on the engine, free up horsepower, and provide more consistent airflow at low speeds or idle. This comprehensive guide walks you through the entire installation process, from selecting the right Spal fan kit to final system testing. Whether you own a Fox-body, SN95, New Edge, or S197 Mustang, these steps apply with minor variations for your specific chassis.

Why Upgrade to an Electric Fan?

Mechanical fans are directly coupled to the water pump and run continuously, regardless of engine temperature. This constant drag robs horsepower — often 10 to 20 hp at high RPM. An electric fan, such as a Spal unit, only runs when needed, controlled by a thermostat or the ECU. Benefits include:

  • Increased horsepower and torque — less parasitic loss means more power reaches the wheels.
  • Improved cooling at idle — electric fans move air even when the engine is at low RPM, preventing hot soak in traffic.
  • Better mileage — the fan only draws electrical power when activated, reducing alternator load.
  • More space under the hood — eliminates the bulky shroud and fan clutch, making room for turbo piping or intercoolers.
  • Quieter operation — no roaring clutch fan, especially on cold starts.

Selecting the Right Spal Fan Kit

Spal offers several electric fan series suitable for Mustang applications. The most common are the S-Blade (high airflow) and Straight-Blade (higher static pressure) fans. For a typical V8 Mustang, a single 16-inch fan rated at 2,800–3,200 CFM is usually sufficient. Some builders prefer a dual-fan setup for extreme heat (supercharged or turbo cars). Choose a kit that includes the fan, mounting hardware, and a wiring harness with relay. Spal USA offers application-specific kits for Fox-body, SN95, and S197 Mustangs. Verify that the fan depth clears your water pump pulley and radiator core.

Tools and Materials Needed

Prepare the following tools and components before starting:

  • Spal electric fan kit (fan, mounting brackets, bolts, and nuts)
  • Wrench set (metric and SAE depending on your Mustang year)
  • Screwdriver set (Phillips and flathead)
  • Wire cutters and strippers
  • Electrical tape and heat shrink tubing
  • Zip ties (various sizes)
  • Multimeter (for continuity and voltage checks)
  • Drill with metal drill bits (for mounting holes if needed)
  • Butt connectors, ring terminals, and a crimp tool
  • Optional but recommended: 40-amp relay, in-line fuse holder, and a thermostat switch or temperature controller (like a Derale adjustable controller)

Preparation Steps

Proper preparation prevents mistakes and damage. Follow these steps:

  1. Park the Mustang on a level surface and allow the engine to cool completely. Hot coolant can cause burns.
  2. Disconnect the negative battery terminal and, if equipped, any positive terminal caps. Secure the cable so it cannot accidentally reconnect.
  3. Remove the radiator cap to release any residual pressure, then reinstall it loosely to keep debris out.
  4. If you have a mechanical fan still installed, remove the fan shroud (usually held by four 10mm bolts) and then the fan clutch. Use a large wrench or fan clutch removal tool to undo the left-hand threaded nut (clockwise to loosen).
  5. Set aside the old fan assembly and inspect the radiator for any damage, bent fins, or leaks. This is a good time to flush the cooling system if needed.

Removing the Old Fan Assembly

For Mustangs that came factory with an electric fan (some late models), you will be removing the OEM fan. For earlier models with a mechanical fan, you’ve already removed it. To remove the electric fan (if present):

  • Locate the electrical connector for the OEM fan and unplug it by depressing the tab.
  • Remove the four bolts (usually 10mm) securing the fan shroud to the radiator.
  • Carefully lift the fan and shroud assembly out, being mindful of radiator fins and hoses.
  • If there are any aftermarket brackets (e.g., from a previous electric fan conversion), remove those as well.

Clean the radiator surface with a soft brush or compressed air to remove dirt and debris.

Mounting the Spal Electric Fan

Spal fans come with a mounting kit that includes brackets or push-through locking pins. Most Mustangs require a puller configuration (fan behind the radiator) to maximize airflow through the radiator core.

  1. Position the Spal fan against the rear of the radiator. Center it so the fan blade covers the core area evenly. For Fox-body and SN95 models, the fan typically sits between the radiator and the engine.
  2. Align the mounting holes in the fan frame with the available radiator core supports. In some cases, you may need to drill new holes. Use a center punch to mark the location, then drill with a 1/8-inch pilot bit, followed by the final bit size (typically 3/16 or 5/16).
  3. Insert the provided rubber bushings or grommets to isolate vibration. Then bolt the fan in place using the supplied nuts and bolts. Tighten to secure, but do not overtighten to avoid cracking the plastic radiator end tanks.
  4. For a dual-fan setup, repeat the process for the second fan, ensuring there is at least a 1/2-inch gap between the two units for airflow.

Verify that the fan blade rotates freely and does not contact any hoses, wiring, or the water pump pulley. Rotate the blade by hand to check clearance.

Push vs Pull Configuration

Spal fans can be mounted as either pullers (behind radiator) or pushers (in front). Puller configurations are more efficient because air is drawn through the entire radiator core. Pusher fans are sometimes used when space is limited (e.g., behind a front-mount intercooler), but they block airflow at highway speeds. For Mustang cooling upgrades, always strive for a puller setup.

Wiring the Spal Electric Fan

Proper electrical wiring is critical for reliability. The fan should be controlled by a thermostat switch or the PCM (if using a factory fan control). Using a relay is mandatory to avoid overloading the ignition circuit. Below is the recommended wiring method.

Basic Wiring Diagram

  1. Mount a 40-amp relay (included with most Spal kits) in a location away from heat and moisture, such as the inner fender well or firewall.
  2. Run a 10-gauge fused power wire from the battery positive terminal to the relay's #30 pin. Insert a 30-amp inline fuse within 18 inches of the battery.
  3. Connect the fan's positive wire to relay pin #87. Use a ring terminal and secure with a nut.
  4. Ground the fan's negative wire to a clean chassis ground point, such as the inner fender bolt. Scrape off any paint for a good connection.
  5. Connect relay pin #85 to a switched 12V source that is only active when the ignition is on (e.g., the wiper motor or fuse box). This ensures the fan can only run with the key on.
  6. Connect relay pin #86 to the positive terminal of the thermostat switch or temperature controller. The other side of the thermostat switch goes to chassis ground.
  7. For manual override, wire a dash switch between relay pin #85 and a 12V source, with a diode to prevent backfeeding. Many enthusiasts install a programmable temperature controller that includes an adjustable turn-on point and A/C override.

Temperature Control Options

  • Thermostat Switch — A bimetallic switch screws into the radiator or intake manifold and closes when coolant reaches a set temperature (e.g., 180°F). Spal offers a 185°F on/off switch.
  • Adjustable Controller — Allows setting the fan turn-on temperature anywhere from 160°F to 240°F. Also provides A/C compressor activation and LED diagnostics.
  • OEM PCM Control — For newer Mustangs (2011+), you can wire the fan to the factory control module using the appropriate harness and a tune adjustment.

Whichever method you choose, ensure all connections are soldered or crimped with heat shrink. Use electrical tape as a secondary wrap. Test with a multimeter for continuity before applying power.

Testing the Installation

After completing the wiring, perform these checks:

  1. Reconnect the battery negative terminal.
  2. Set the multimeter to DC volts and verify 12V at the relay pin #30 with the key off. With key on, check pin #85 and #86 for voltage.
  3. If using a thermostat switch, temporarily bypass it by connecting pin #86 directly to ground. The fan should activate immediately. This confirms wiring is correct.
  4. Remove the bypass and reinstall the thermostat switch. Start the engine and allow it to reach normal operating temperature (around 190°F-200°F). The fan should turn on within a few minutes. If not, check the switch's calibration or the coolant flow around the sensor.
  5. Let the fan run for several minutes, ensuring it draws air through the radiator. Check for any unusual noise or vibration. Adjust mounting if needed.
  6. Monitor the temperature gauge or OBD-II scanner. The fan should cycle on and off, maintaining a steady temperature.

Final Adjustments and Tidying

  • Secure all wires with zip ties, keeping them away from belts, pulleys, and the exhaust manifold. Use wire loom for extra protection.
  • Double-check the fan mounting bolts are tight. Over time, vibration can loosen them, so consider using a thread locker (Loctite 242) on the nuts.
  • Reinstall the radiator cap and top off coolant if you drained any. Bleed air bubbles by running the engine with the cap off until the thermostat opens.
  • Take the car for a short test drive, then stop and check for any electrical hot spots (overheated wires or connectors).
  • If you installed a manual override switch, label it clearly.

Troubleshooting Common Issues

Fan Doesn't Turn On

  • Check fuse and relay operation. Swap the relay with a known good one.
  • Verify ground connections. Use a multimeter to test continuity.
  • Test the thermostat switch by heating it with a heat gun (or submerging in hot water). It should close at its rated temperature.
  • Ensure the coolant level is correct and the engine actually reaches the switch's trigger temperature.

Fan Runs Constantly

  • A shorted thermostat switch or controller can cause constant operation. Unplug the switch; if fan stops, replace the switch.
  • Wire misrouting: Check that fan control ground is not connected to a constant 12V source.
  • Some controllers have an "A/C override" that keeps the fan on when A/C is engaged. If the A/C is off, verify that override pin is not inadvertently grounded.

Fan Makes Noise

  • Blade contact with frame — re-center the fan and check for bent blades.
  • Mounting vibration — add rubber washers or tighten bolts evenly.
  • Electrical whine — install a noise filter on the power wire if fan motor generates RFI.

Maintenance Tips

Electric fans require minimal upkeep. Periodically inspect the blade for debris, clean the motor housing with a dry cloth, and ensure the wiring does not chafe against metal edges. Every oil change, check the fan operation by letting the engine warm up. If you notice slower start-up or increased current draw (fuse blows), the motor bearings may be failing — replace the fan as a unit.

Conclusion

Installing a Spal electric fan conversion in your Ford Mustang is a rewarding upgrade that enhances cooling performance and frees up horsepower. By taking a methodical approach—selecting the correct fan size, mounting it securely, wiring through a relay and temperature switch, and testing thoroughly—you can enjoy reliable, efficient engine cooling in any driving condition. Whether you’re building a street machine or a track-focused pony, an electric fan is a proven step toward better thermal management. For further reading, check out this detailed Corral.net write-up or the Spal universal fan installation manual (PDF).