RV AC Unit Humming But Fan Not Running – Why & How To Fix?

Exploring a new weekend getaway with your RV on a hot summer day sounds good. But the outing won’t be that pleasant if the RV AC unit hums but the fan doesn’t function. Why is it so?

Several reasons contribute to the RV AC unit humming, but the fan is not running. Faulty capacitors, loose wiring, and malfunctioning fan motors are some of the significant reasons.

We’ll be exploring all these elements in this write-up. Therefore, without wasting a second, let us begin!

RV AC Unit Humming But Fan Not Running

What Are The Components In The RV AC Unit?

It’s the internal components and the parts associated with the AC fan that malfunction, creating the problem we are discussing. 

Knowing how these parts function is crucial because it will help you precisely understand what goes wrong.

Let us know some of those major components that may go bad.


It is the core element of the AC unit in your recreational vehicle. The compressor’s task is to regulate the refrigerant in the AC unit’s system. This refrigerant is stored in a closed circuit and transformed into a liquid.

Before going to the evaporator, this liquid goes into the pipe system. Heat extraction takes place from the external environment, which cools the evaporator. 

The cycle continues when the refrigerator flows back to the compressor. Thus, the vehicle interior is cooled down.

Fan Motor

It is an integral part of the cooling system, keeping the AC fan running. You’ll find the motor in the condenser of your RV’s AC unit. For easy identification, just notice the vents on the top of the motor.

That said, there is a condenser and a blower fan motor. Both of these motors work together to maintain a balance in air circulation. 

The condenser motor relieves warm air inside, and the blower motor is responsible for cool air output. 


The primary task of the condenser in the AC unit is to squeeze out heat from the air and then flow it out. Internally, refrigerant vapors go under a cooling mechanism, reusing them as liquid. 

The total cooling results from refrigerant vapors passing through coils in the condenser. 

In addition, the condenser plays a big part in the effectiveness of the refrigerant as it uses a higher saturation temperature than usual to cool it down.

Read Also: RV AC Freeze Sensor Location [Complete Guide to a Freeze Sensor]


The evaporator’s core job is to absorb heat from hot air. Cooled-down liquid is passed through the evaporator and takes part in heat absorption from the hot air produced in your RV.

The entire mechanism helps in the expansion of the liquid. Since it’s part of a cycle, the liquid becomes vapor, and the compressor consumes it. In this way, the cycle goes on for keeping your RV cool.

Reasons Behind RV AC Unit Humming But Fan Not Running

Your RV AC unit making a humming sound with the fan not functioning is a possibility of multiple issues. 

It is a sign that can even lead to a possible AC unit failure if you don’t take immediate measures. Below are some of the most common reasons behind the humming sound:

  • Faulty thermostat
  • Inadequate coolant for the cooling cycle
  • Loose wiring and faulty connections
  • Coils are frozen with ice
  • Dirty and clogged drain
  • Faulty fan motor 
  • Bad capacitors 
  • Mechanical issues with fan blades

Read Also: RV AC Soft Start Vs Easy Start Kit | Which One is Worth it?

5 Potential Fixes For RV AC Unit Humming But Fan Not Running

Your RV AC unit’s humming and fan not running problems have multiple fixes. Depending on the existing situation, there are different approaches you can try as fixes. Let us explore those in the section below;

1. Replace Bad Capacitors 

The capacitors are going bad, resulting in your RV AC unit’s fan motor not starting. You’ll hear a humming-type noise from the unit whenever it happens. 

Replacing isn’t complex, but you must know the essential electrical functions. In this regard, you should go to the top of your RV and open the AC compartment.

Source: https://www.youtube.com/watch?v=QaqbaLsQS8E

The next step would be to take out the capacitor and check the necessary parameters that you must know for a compatible new capacitor.

Source: https://www.youtube.com/watch?v=QaqbaLsQS8E

Carefully hook up the wires with the newly replaced capacitor. Finally, you’re done with the replacement of capacitors.

2. Fix Faulty Wiring

If the wires are damaged or malfunctioning, it will harm the AC unit and hamper the fan’s running. As a precaution, you should turn off the power for your own safety. 

Always inspect the wire’s appearance before deciding to replace it altogether. You should track one wire at a time to avoid hazards. Use suitable connectors or pins; if the wire requires cutting, carefully carry it out with scissors.

Read Also: 6 Reasons Why Does RV AC Compressor Start and Then Stop

3. Unfreeze The Coils

Ice accumulation in the condenser coils is a significant issue to deal with. To fix this issue, you just need to expose the coils. Your task should be to let the ice melt by opening up the AC vent.

Besides, you should consider that ice forming on the coils means the thermostat is faulty. Anything like this means you should take measures to replace the thermostat. 

4. Take Out Fan Blockages

The fan may not run in your AC compartment due to something blocking it. It can be the broken fins or anything adjacent that halts the spin. 

Use pliers, screwdrivers, and flashlights to open and inspect the thing causing the block. Once you locate the item inside, ensure its removal accordingly.

5. Clean The Drainage

AC Unit drainage blocked with debris and residue causes massive issues. Halting normal AC operations is a high possibility. 

You must consider certain aspects if your RV’s AC is making a humming sound. Cleaning the drainage line adequately will mitigate the issue.

Read Also: Adding Second AC to 50 Amp RV: A Complete DIY Guide

Prevention Tips For RV AC Units Humming But Not Running

The AC unit in your RV can run smoothly without any problems with unwanted humming or the fan stopping to operate. Following are some directives that’ll help you avoid these issues:

  • Set a proper thermostat configuration and regularly monitor it
  • Keep the AC unit clean and ensure that the drain or the fan doesn’t get clogged with debris
  • Always check the condition of the wiring and mitigate faults upon detection
  • Ensure that the coils in the condenser are clean and not frozen
  • Try to cover up the RV AC unit to avoid external issues when the RV is not in use
  • Try to oil the fan with mechanical oil

Is Expert Consultation Required For RV AC Unit Fan problems?

You can solve Certain RV AC unit fan problems with basic electrical knowledge. But if you are new, it is better if you seek professional help. 

There are safety issues associated with it because of the electric elements. In addition, complexities arise when you must replace the fan motor or core elements like the compressor.

Read Also: How to Solve RV AC Clicks But Won’t Turn On Problem?


The humming sound in your RV AC unit and the fan not running may need to be clarified about things to do. We have added some of the most frequently asked queries by people who have faced this problem. Let us look at those!

Can low levels of coolant in an RV AC unit cause RV humming? 

The coolant or refrigerant level going low has a high possibility of resulting in a humming sound. That is why keeping the coolant level constantly in check is required.

How to know if an RV AC capacitor is faulty?

The most basic symptom of an RV AC capacitor going bad is warm air from the vents. If you see a humming sound or burning smell coming from the vents, it is also a sign of capacitor failure.

Final Thoughts

A comfortable outing with your RV is ensured when it’s fully functioning. In hot weather, your RV without AC is unimaginable. Therefore, it is required to mitigate all issues before. 

The humming problem can be easily avoided if you properly maintain the AC unit. We recommend you check and try the easy fixes before seeking professional help to change certain faulty parts.

Read Also: Ducted vs. Non-Ducted RV AC: What Should Be Your Choice?

Similar Posts