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HomeTips & GuidesDual Fan Relay Wiring: How to set up a Car Dual Fan

Dual Fan Relay Wiring: How to set up a Car Dual Fan

Learn everything about the dual fan relay wiring from this comprehensive guide. Here, you will learn the basics of wiring your car’s dual cooling fans. Also, we’ll explain separately and in detail how you can control the dual cooling fans. 

Therefore, read on for these and other critical details on this topic. 

Is there a Harm to Using One Relay for Dual Cooling Fans?

Some people often use a single relay to control their dual cooling fans. While this will still work, it is wrong. Primarily because it renders your system inefficient, this practice also harms your relay fuse

Usually, most of the cooling fan relays have a 30A fuse. Therefore, when you use a single relay to control dual fans, the current draw is higher than the fuse rating. Hence, this can cause the fuse to blow. 

If it survives the current draw, the power can also be insufficient to run the entire system. The alternative would be a single relay controller with a high current rating.

But this will cost you a lot, although you can consider the option if you’re keen on saving space. 

How Do You Wire Dual Cooling Fans?

Dual Cooling Fans Button. 

Dual Cooling Fans Button. 

Here is the circuit diagram for wiring dual cooling fans:

Dual Fans Relay Wiring Circuit Diagram

We recommend using a 40A relay because it is easy to work with and can handle the circuit’s current demands. You will note that the dual cooling fans feature positive terminal wires that are marked.

Connect these wires to the relay’s yellow wire. Again, if you’re using the standard 40A relay, the colors should be easily identified from the color codes. The relay also features black cables that you should connect to the switch to complete the circuit. 

Finally, you will notice a red cable on the relay that you still haven’t connected. It is where you should connect your fuse. The fuse should be between the battery/power source and the relays. 

Also, note that you will need a thick cable on this part of the circuit because this is where we place the load. Ideally, the least wire gauge should be 14. Any other thick wire will be appropriate.


That’s all you need to do for a simple dual-cooling fan relay wiring. You can do all this without involving a mech with the circuit diagram we provided. The processes are straightforward, so go ahead and do the job. 

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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