What to Do When Your RV Converter Fan Isn’t Working

Your RV uses a power converter to transform AC power, usually from a shore power cord or running generator, to 12-volt DC. The converter is a piece of machinery with many unique parts, each with an important job to do. If you’ve gone through the trouble of finding out what, exactly, is causing your converter to malfunction and narrowed it down to the fan, you have more work to do yet.

You’ve discovered that your RVs converter fan is not working. Running a test to troubleshoot your RV converter fan will verify the true root of the issue. 

To find out why your RV converter fan is not working, you can take a look at either the batteries or the thermostat. When you check the batteries, use a multimeter to test for a constant power load. Testing the thermostat is more intensive, and should be seen to by an electrician. 

RV Converter Fan Not Working 

When your RVs converter fan is not working, you can try a few different angles to discover the source. Testing the battery is a less invasive manner of assessing the fans. 

If you test the battery and see that it is working fine, you may need to dive deeper and inspect the thermostat or temperature gauges.


There are a few reasons why an RV converter may malfunction. One common source is that the batteries are not working at full power.

The way to verify this is to test the batteries using a multimeter. Disconnect the vehicle from any external power source, allowing you to use your vehicle with only the onboard battery.

Then the batteries, connected in parallel, should be disconnected from each other. You may find that they are connected in parallels, or in series. You will be able to know that the battery is connected in parallel by seeing if each positive terminal is connected to the next positive terminal.

Wait 20 to 30 minutes for the batteries to rest after you turn them off. This resting period will allow you to obtain the most accurate reading.

Use a multimeter, set to the voltage setting, and test one battery at a time. You are looking for a constant load. If you are not witnessing one, it means that one of the batteries in the converter is faulty. If the battery is faulty, it is not able to power the fan adequately.

Temperature Sensors

Before you open the converter up, decide if it would be in your best interest to call a repair person or electrician first. This process is going to leave live components bare and unprotected in a very tight compartment. You will need to have the 120-volt power on during this in order to test it correctly.

If you are not 100% confident in your ability to undertake this electrical-component-heavy task, consult an electrician. Working with these components can be extremely dangerous to an untrained hand.

Step One 

The first step is to disconnect power from the converter. You will need to unhook from shore power, or shut down the generator, if you are using one. If you have a feed running toward your 12-volt circuit, disconnect this as well.

Step Two

Now, you’re going to remove the case around your converter. Typically, RV converter manufacturers are not expecting owners to diagnose their own converters. Because of this, the converter case will likely not have visible screws or bolts for you to remove.  

Know that if you remove the rivets or spot welds that hold the converter case in place, you may be invalidating your warranty. Once again, only do this yourself if you were a competent electrical engineer with the needed diagnostic equipment.

Step Three 

Once you have the converter case removed it should not be difficult to find the fan. Inside this case, you should find a solenoid, a number of diodes, the transformer itself, and a circuit board. The circuit board monitors and manages the charge to the coach batteries. You may also notice a printed circuit board – this accommodates your capacitor and a number of resistors.

As this is a printed circuit board, be very careful not to damage the printed circuits or any electronic parts as you remove the board to access the fan. However, due to the structure of your converter, you may not need to interact with it to get to the fan.

Importantly, within this box, you will find two AC wires and three DC wires.

Step Four 

Restore 120-volt power only to the converter, as you will need it to test out the voltage running to it. At this point, there are now live components exposed to the very tight space in which you will be performing these tests. The fan inside the converter is a 120-volt component. That is why you need to have 120-volt power on.

Step Five

Finally, you were going to test the thermostat / temperature sensor. The thermostat or temperature sensor are what controls the fan. Using a shrink wrap gun, heat gun, or hair dryer, blow hot air into the heat sink. Use a multimeter to test the amount of power passing to the thermostat as it heats up.

Continue to test it after it is heated, to see if the voltage changes. If you do not see 120-volt power passing from the thermostat after it heats up, then the thermostat or temperature sensor unit is faulty.

Alternatively, if the thermostat is functioning, and power is conveyed to the fan, but you still don’t see the fan starting, then the issue lies with the fan.

Before you replace either component, disconnect the open converter from 120-volt power.


When your RV converter fan is not working, you should look to either the batteries of your converter, or to the thermostat for the cause. To test the batteries you will need to connect them to a multimeter after disconnecting the vehicle from any external power source. If you find it they are not delivering a constant loadout, they are the problem.

Or temperature sensors and see that the power is being conveyed to the fan without it actually starting, then something about the fan has gone faulty. You may need to replace it in that case. If you do not see 120 volt power passing from the temperature sensor, then it is actually what is causing your fan to not work.