How to Wire Dual Electric Fans

As many of you are aware, clearance between the front of your engine and the radiator can be extremely limited. Most of the time, your first thought is to find the smallest single electric fan that is powerful enough to cool your car, but there is another option! Dual electric fans could be the answer to your cooling problems. “I don’t know how to wire up dual fans,” you might think. We are happy to assist you in understanding the process. Dual electric fans have several advantages, including the ability to pull more cfm between the two fans than a single fan, allowing more clearance for front-engine accessories, and covering more of your radiator’s core for efficient airflow and cooling without having to fabricate a custom fan shroud that you may not even have the room for. Installing dual electric cooling fans covers more of the core surface area of your radiator.

How to Wire Dual Electric Fans

How Do You Connect Two Cooling Fans?

A dual fan setup can be wired in a variety of ways. Dual relays, for example, could be used to control each fan separately. This is an excellent option for controlling one fan based on engine temperature and the other based on the air conditioning load (the second fan activates when the compressor engages) or with a manual switch. A single high-current relay could be used to control both fans if desired. The diagram provided below, which uses dual relays with a single temperature sensor, is both the most reliable and easiest method we’ve found for wiring dual fans. It makes use of a 40-Amp Electric Relay Kit as well as an Electric Fan Sensor. The relay separates the high amp load of the fan circuit from the switching circuit, while the temperature sensor controls the fans on/off operation based on the temperature of your engine’s coolant.


Is it safe to use a single relay to power two cooling fans?

If you’re going to use a single relay for dual cooling fans, make sure it’s a high-current relay that can handle the combined fan output. We’ve seen people wire up dual fans with a single standard relay to control both fans. We discovered that this is inefficient and potentially dangerous, as most dual fans pull enough load in amps at startup to blow the fuse for the single relay. This is typically a 30-amp fuse to protect the wiring and relay, which is insufficient to support dual fans operating at the same time. A high-current single relay controller can frequently handle this task, but at a higher cost than two simple relays, as shown in the diagram below. If you’re tight on space in your engine bay, a single high-current relay is an option.


Is it possible to control dual cooling fans separately?

Yes, you can control two fans independently. Dual thermostatic switches, for example, can control each fan separately. This method necessitates the use of a second temperature switch, some additional wiring, and, of course, dual relays. Some people prefer to have the second fan on a manual switch for “emergency” cooling, whereas others wire their second fan to use the air conditioning compressor signal to engage the second fan. To control one or both fans, there are fancy controllers and in-dash temperature gauges with fan outputs, as well as cooling fan outputs on most aftermarket fuel injection systems. Controlling the fans individually can be useful in some situations, but it is usually unnecessary extra work, as most of the time you only want your fans on to cool the car down before turning them off. We used two curved blade universal electric cooling fans for this setup. These are available in diameters of 8, 10, 12, 14, and 16 inches to fit almost any downflow or crossflow radiator application. These fans can be directly mounted to the core using a nylon mounting kit, or if you have the space, a full aluminum fan shroud can be used to cover the core of your radiator.


Dual Radiator Cooling Fan Wiring Procedure

The use of a standard 40-amp relay simplifies fan wiring.

To help simplify the wiring process, the color-coded diagram below corresponds with the wires on the relay kit we mentioned earlier. Begin by connecting both of the positive wires from the fans to the yellow wires on each relay. The blue wires on the relays must then be connected to switched power (usually from your ignition switch, but modern replacement wiring harnesses usually have a fused fan relay trigger wire). The black wires from the relays are then spliced together and connected to the thermostatic switch. Finally, connect a fused constant power supply to both red wires on the relays. This is the relay’s load side, and you should use at least 14-gauge wire here. The relay pigtail’s white wire will not be used. With these dual fans wired together, you can keep your car cool without worrying about clearance issues!

Dual Fan Wiring