How To Straight Wire A Cooling Fan?

Learning how to straight-wire a cooling fan is a vital DIY skill. It will help you overcome overheating problems when you have a faulty radiator fan.

A vehicle’s engine cooling fan is designed to redirect and release excess heat from the engine compartment. Simultaneously, the cooling fan draws in fresh air to cool off the engine.

If your car’s cooling fan suddenly stops, do not panic. It may not be as severe as your mind may magnify the occurrence. All you need to do is test the component by straight-wiring the cooling fan.

How to Straight Wire a Cooling Fan

The combustion process in a vehicle involves several components within the engine compartment. This complexity in their working generates so much heat that can damage the engine if not properly managed. This is why the cooling fan is essential.

However, you may find out someday that the cooling fan has stopped. This occurrence can lead to overheating and damage to the vehicle’s engine. So, the best way to overcome this challenge is to bypass the normal circuit of the fan and straight-wire it to the engine.

The following are step-by-step procedures on how to bypass the radiator fan and straight-wire it to the vehicle’s engine.

Identify the cooling fan’s positive and negative wires

Firstly, take a moment and locate the cooling fan’s wires – both positive and negative wires. Then, cut and strip off 1/2 an inch from the ends of the wires’ insulation.

Connect a 12-gauge jumper wire.

Get a 12-gauge jumper wire and connect one of its ends to the cooling fan’s black ground wire. Then, connect the jumper wire’s other end to the car’s engine block or a metal part on the vehicle.

Connect another jumper wire.

Get a second 12-gauge jumper wire and connect one of its ends to the cooling fan’s positive wire. Stretch out the 12-gauge jumper wire and extend its other end to reach the vehicle’s battery. After that, you can test it by placing the wire on the battery.

Once you place the other end of the second jumper wire on the battery’s positive terminal, the cooling fan will turn on and start spinning.

If it works, the cooling fan is still in good condition. Meanwhile, you can also decide to find out how to wire a cooling fan to toggle switch and use this approach. It will help you manage the operations of the cooling fan efficiently without any hassle.

Read Also: Radiator Fan Runs When Engine Is Cold – Causes & Fixes


Can you straight-wire a cooling fan?

Of course, you can straight-wire a cooling fan. The process of straight-wiring a cooling fan is not rocket science; you can learn to do it perfectly.

DIYers are always excited whenever they have an opportunity to learn something new about their car. They enjoy fixing minor faults that may not require extreme automobile repair knowledge.

Being a DIYer is one way to avoid spending so much of your hard-earned money repairing your car when a component is faulty. Some faults can be as minor as requiring reconnecting a loose cable.

However, if you are scared of fixing the problem, you may end up spending money at an auto mechanic’s shop paying for something you could handle. Wiring a cooling fan is one of those tasks you can handle.

Can I hardwire my radiator fan?

Sure, you can hardwire your car’s radiator fan to make its operations effective. Your car’s radiator fan needs about 15 amps on average for its operation. The fuse relay box beneath your car’s hood also contains a relay that helps the radiator fan function.

The relay possesses about four terminals, and one of them is constantly hot, even when the key is off. The terminal that actuates the relay becomes hot when you turn on the key.

This particular terminal that actuates the relay conveys low amperage from the key. It cannot carry the amount of amperage a car’s radiator fan needs; otherwise, it will spark up a fire.

In that case, the solution is to hardwire the fan with at least a 12-gauge wire that is capable of conveying the amount of amperage. You may have to find out how to wire an electric fan with a relay to do it correctly.

How many amps does a radiator fan draw?

You must note that the more powerful your vehicle’s radiator fan is, the more current it will require. Your vehicle’s electrical system must possess the amount of amperage the radiator fan needs for it to work perfectly.

Typically, 12 to 16-inch radiator fans require between 15 and 28 amps to work efficiently. If you have a dual radiator fan application, the components can draw anything around 35 amps or thereabout. Other radiator fans can draw as much as 13.5 volts.

Ensure to ascertain the kind of radiator fan in your vehicle to know the exact amount of amps the system utilizes. If the power requirement of the fan is too high, you may want to incorporate an electrical system that can supply the amperage.

Can I drive my car if the fan is not working?

Driving a car with a bad radiator fan is possible; however, it is not ideal. The fan is solely responsible for blowing cool air into the engine compartment to cool down during high temperatures. It doesn’t really play a role in the car’s motion.

Although the radiator fan does not play any role in a car’s motion, it ensures safety. The component ensures that the vehicle does not overheat, thereby leading to engine problems that can be costly to repair.

If you must drive your car when the fan is not working, you would need cool weather and a traffic-free zone. In most cases, these two factors are not predictable. So, to be on the safe side, kindly find out how to make the radiator fan turn on.

How many amps does a 12v fan use?

A 12V fan typically uses about 0.6 amps. Fans draw current based on their sizes and speed when working. While some may require less than 1 amp, others may need something more.

You can determine the amps a fan uses by applying the Watts equation. The formula is Volts X Amps = Watts. That means Watts divided by Volts will be equal to Amps. On the other hand, Watts divided by Amps will be equal to Volts.

Since a 12V fan gives an electricity output of 8 watts, the Watts equation will be: 8 watts divided by 12 Volts = 0.6 or approximately 0.7 amps.

Do radiator fans always spin?

Radiator fans do not consistently spin because the system is programmed. The fan turns on and starts spinning when the temperature-sensitive switch signals the system of a high temperature.

When the temperature becomes low again, and the system cools down, the switch also sends a signal. Once the system receives the signal that the temperature is low, the fan will go off.

The standard temperature of a vehicle’s engine coolant that triggers the fan is 200 Fahrenheit. Once the engine coolant’s temperature reaches this level, the radiator fan will start spinning to draw air to cool down the system.

If your car’s cooling fan is constantly off, you may have to find out how to wire the radiator fan to stay on. Then attach a toggle switch to enable you to engage and disengage it at intervals. This can help in the meantime until you decide to change the system.

Final Words

This article has just explained the simple steps of how to straight-wire a cooling fan. This is a rescue strategy for you whenever you suspect that your car’s cooling fan is faulty.

It is crucial for you to do everything possible, never to drive when your car’s cooling fan is not working. It will save you the stress of further damage due to overheating.

Ensure to follow the procedure above to straight-wire the cooling fan to ascertain whether it’s still in good condition or not. If the fan does not work, you may have to replace it. If you are not sure about doing the job perfectly, kindly consult an expert auto mechanic.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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