RV Fuse Box Fan Running: What You Need To Know

Do you hear your fuse box fan running? Is this normal? The good news is that a fuse box fan running is normal.

Your RV fuse box is the one-stop shop for your entire RV electrical system. It converts your shore power (dc power) or distributes it (ac power) to allow for your lights, outlets, and even an appliance. And with all that work, some heat is generated that a fan needs to provide cool air.

The most common reason your RV fuse box fan runs is that your built-in converter generates heat.

Heat is generated when the power converter changes ac power (shore power) to dc power (battery), and the cooling fan will run periodically. This post will review why your fuse box produces heat and how the fan is critical to operating your electrical system safely.

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As you look at your RV circuit breaker panel, it likely looks different than any other panel you have seen. It is especially different from a house panel in that circuit breakers and fuses are out of the same box.

However, the RV fuse panel is the same as your house panel in that the wire and breakers are an ac circuit breaker and provide ac power to things like your air conditioner. If you have an electrical issue, you can have a circuit breaker trip and easily reset it to gain back power.

Since a circuit breaker is 120v ac power, the same as your shore power, there is no converting of electricity. And since there is no converting, no heat or fan is needed.

Any heat that is generated and the reason you need a fuse box fan is because of the battery power needed in your RV. Let’s look at this battery power and why it causes the fan to run.


We just recapped the one half of an RV electrical system, which was the 120 volt side. The other half is the battery power and fuses. This part of your breaker box is where 12 volt dc is provided. If you have a blown fuse, this is where you would inspect and replace it as needed.

This dc power is what you need to power your lights and even critical appliances such as a furnace. Here is a complete list of what the battery powers in a travel trailer.

You only have a cooling fan for your fuse box because you are converting ac power into dc power or battery power. And this is where your RV converter comes in.


The power converter takes your 120v ac from shore power and “converts” it to 12 volt dc power. And since there is a power conversion, heat is generated, and the converter will signal to turn on the fan motor. Think of the converter just as a battery charger. As you are plugged into shore power, that battery is charged to keep up with the demand.

Under normal circumstances, the cooling fan runs periodically. The converter can cool itself down fairly quickly with normal loads and proper ventilation. However, some issues can arise where the fan runs continuously. If you have a situation where the converter fan is running continuously, you may have an issue that can be addressed in my post link.

Final Thoughts

When your RV fuse box fan is running, it is a sign that your converter is working and needs to cool off for a minute. The converter is a charger that takes your ac shore power and converts it to dc battery power. With that conversion of power, heat is generated, and a cooling fan is needed. This is normal when the fan runs periodically and should not be an issue.