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RV AC Unit Humming But Fan Not Running: 10 Practical Solutions

Is your RV AC unit humming but fan not running? Don’t worry! I have also been through this frustrating issue, and I know how to deal with it like a pro. The possible reasons behind this problem are blockage in the fan, a faulty capacitor, and an over-used motor.

Read this guide as I will share 10 easy solutions to fix AC humming. Moreover, I will also share some helpful maintenance tips. With that, let’s get into the details!

RV AC Unit Humming But Fan Not Running: 10 Fixes Listed!

The Working Process of the RV AC Unit

RV AC units work similarly to air conditioning systems in residential and commercial buildings. However, they are specifically designed for the unique challenges and constraints of RVs. Here, I will give you a basic overview of how recreational vehicle AC units work to keep your vehicle cool:

  • Compressor Function: First and foremost, the compressor initiates the process by circulating, heating, and compressing refrigerant vapors within the AC unit, raising their pressure significantly.
  • Condensation: Then, the condenser removes heat from the pressurized vapors, expelling it from the vehicle. So, the refrigerant vapors cool down in the condenser, transforming back into a liquid state.
  • Evaporation: Afterward, the evaporator receives the cooled liquid from the condenser and absorbs heat from the warm air inside the RV. This causes the liquid to expand, and once it absorbs sufficient heat, it transitions back into vapor.
  • Vapor Return: The heated vapor is drawn back into the compressor, initiating a repetitive cycle.

RV AC Unit Humming But Fan Not Running: Problems and Fixes Table

Before diving into the details of each problem and its solution, let’s take a general overview to prepare your mind for what comes next.

Causes

Fixes

Blockage in the RV Fan:

Regular Cleaning, Mesh Screens, Insect Repellents

Issues in the Capacitor:

Routine Maintenance, Capacitor Inspection

Over-Used Fan Motor:

Regular Lubrication, Power Conditioner for Stable Supply

Faulty Thermostat:

Manufacturer Guidelines for Calibration, Wiring Examination, Battery Replacement

Tripped Breakers in AC Units:

Inspect Electrical Panel, Restore or Replace Fuses

Malfunction of Fan Relay or Control Board:

Multimeter Testing, Board Replacement if Damaged

Fault in the Wiring:

Upgrade Wiring with Heat-Resistant Materials, Routine Inspections

Mechanical Wear and Tear:

Corrosion-Resistant Coatings, Replace Worn-out Parts, Proper Insulation

Rust Related Problems:

Surface Rust Removal, Seal, and Cover When Not in Use

Condensors Freezing Up:

Check and Refill Refrigerant Levels, Refill Refrigerant

10 Best Solutions For Fan Not Running Issues

Now that I have highlighted the issues with the RV fan motor and solutions, it’s time to dive deep into the fixes for better understanding. Let’s check them out:

Problem #01: Blockage in the RV Fan

Since I bought my recreational vehicle, the obstruction in the fans is the most irritating problem I have faced. It can be a result of a variety of factors, as RVs go through some harsh weather and environmental conditions. Some common reasons behind this AC fan obstruction are given below.

Problem #01: Blockage in the RV Fan
  • Dust, dirt, and debris can accumulate in RV fans over time, especially if the RV is used in dusty or wooded areas.
  • Parking or driving under trees can result in leaves, twigs, and other tree debris getting lodged in the RV fan system.
  • Insects, such as wasps or bees, may build nests in or around the fan blades, causing blockages.
  • External factors like heavy rain or snow can contribute to the accumulation of moisture, making it easier for debris to stick and cause blockages.
Solution

You have to act quickly and apply the following measures at the first signs of air conditioner unit fan blockage.

  • Clean the fan and surrounding areas to avoid blockade in the RV fan motor.
  • Also, consider installing mesh screens on vents to prevent larger debris from blocking the fan blades.
  • Always park your RV in open areas when feasible. In addition, use RV covers or parking awnings to shield the RV from falling leaves and twigs.
  • Regularly inspect the fan and vents for signs of insect activity. Plus, you can utilize insect repellents or deterrents around the RV fan.

Problem #02: Issues in the Capacitor

You may also hear a humming noise from the AC unit due to the faulty capacitors. Let’s get into the details of why your fan capacitors may face these issues over time.

  • Capacitors have a limited lifespan, so with time, they undergo wear and tear.
  • AC fan capacitors are susceptible to damage from issues such as overheating or abrupt power surges.
  • In certain instances, damaged capacitors may exhibit physical indicators, such as swelling or other visible signs of harm.
Solution

To avoid and solve these capacitor-related problems, I recommend you try out the following solutions.

  • Implement a routine maintenance schedule to identify and get aging capacitors replaced.
  • It is wise to install voltage regulators to ensure that the voltage supplied to the fan capacitors remains within the specified range.
  • Replace the capacitors that indicate signs of damage, such as swelling and leakage.
Problem #02: Issues in the Capacitor
Credit: www.youtube.com @Doing Things Dan’s Way

Problem #03: Over-used Fan Motor

Similar to any mechanical part, the motor has a finite lifespan. Prolonged usage and the natural aging process can contribute to the degradation of its internal components. Other than this, several other reasons can cause fan motor burnout.

  • Inadequate or deteriorated lubrication within the motor’s moving parts can increase friction, leading to overheating and eventual burnout.
  • Irregularities in the electrical supply, such as power surges or fluctuations, can contribute to the deterioration of the motor and potentially lead to burnout.
Solution

As an RV owner, I also faced motor burnout issues. However, these simple fixes have now made my life a lot more easier.

  • Keeping the motor adequately lubricated at all times and using the recommended lubricants as per the manufacturer’s guidelines.
  • Utilizing a power conditioner to provide a stable power supply to the motor.
  • Replacing the motor when it adds no reading or displays signs of being burnt out.

Problem #04: Faulty Thermostat in RV AC Unit

The thermostat plays an important role in controlling the temperature of your RV. However, the following issues in this device can cause a malfunction in the air conditioning unit.

Problem #04: Faulty Thermostat in RV AC Unit
Credit: www.youtube.com @John Marucci
  • Incorrect calibration leads to the thermostat displaying inaccurate temperatures.
  • In digital thermostats, faulty wiring or a depleted battery can hinder proper functioning.
Solution

When you encounter a faulty thermostat, I recommend you apply the following practical solutions:

  • Consult the manufacturer’s guidelines for calibration.
  • Examine the wiring by opening the panel to confirm secure and intact connections.
  • Replace old batteries.

Problem #05: Tripped Breakers in the Air Conditioning Unit

Abrupt electric supply is a common reason that causes every electric part in the AC unit to malfunction. In addition to this issue, your air conditioner breakers can be tripped due to the following reasons.

  • Running multiple power-consuming devices at the same time can overwhelm the circuit and trip breakers.
  • The occurrence of internal shorts within the air conditioner unit can cause breakers to trip.
Solution

You can fix and avoid breaker tripping by following these simple steps.

  • First, you need to inspect your RV’s electrical panel to look for any off switches or blackened fuses in the circuit. If you find such problems, safely restore the breaker to its original position or substitute any blown fuse.
  • To fully avoid frequent tripping, connect your recreational vehicle to a stable and reliable power source. As discussed before, fluctuations in power can strain the AC and trigger breaker trips.
Ricky Smalls
Connecting to a stable shore power will eliminate your doubts about the power issue. If your AC still produces a humming noise after getting stable power, then the culprit is not the power source but the unit itself.Ricky Smalls, An Avid Camper, and Senior Writer at Camperlife

Problem #06: Malfunction of Fan Relay or Control Board

The fan relay turns the RV AC fan on and off, managing airflow. On the other hand, the control board oversees the entire AC system, controlling temperature and making sure everything works together for effective cooling in the RV.

Both these components team up to ensure optimal performance and climate control within the RV. These components can experience malfunction due to:

  • Electric Glitches;
  • Overloading of electric systems;
  • Aging of these electric components.
Solution

I also faced this issue last summer, and I found a solution to this the hard way. But, lucky for you, here are the 3 steps that’ll help you fix this issue:

  • Utilize a multimeter to test the continuity of the fan relay.
  • Examine the control board for visible signs of damage.
  • In case the board appears fried or damaged, consider acquiring a new one.

Here’s a related video that will give better insights.

Problem #07: Fault in the Wiring

RVs also face wiring issues due to the intense heat throughout the day. Over time, connections may undergo corrosion or wear and tear. Additionally, if your air conditioner is not installed correctly, it could result in potential wiring issues in the future.

Solution

If you regularly travel on your RV during intense sunny days, I suggest you apply these preventive measures to avoid faulty wiring.

  • Upgrade wiring with heat-resistant materials and ensure proper insulation to withstand intense summer heat.
  • Conduct routine inspections to identify and address corrosion or wear in connections before they escalate into major wiring issues.

In addition to these common fixes, you should also ensure the correct installation of the AC unit by hiring a qualified professional to prevent future wiring complications.

Problem #08: Mechanical Wear and Tear of RV Air Conditioner

As an AC unit ages, a combination of these factors contributes to wear and tear, eventually affecting its overall performance and efficiency.

Problem #08: Mechanical Wear and Tear of RV Air Conditioner
Credit: www.youtube.com @DIY JIM
  • Continuous operation causes friction between AC components, leading to gradual wear.
  • Outdoor air conditioning units exposed to weather conditions may experience corrosion, which can weaken metal surfaces and structural integrity.
  • AC refrigerants and lubricants degrade over time, leading to inadequate cooling and increased strain on components.

All these issues will eventually combine to cause a humming sound in your AC unit.

Solution

In order to avoid these issues, I adopted the following strategy to identify and stop mechanical wear and tear before time. You can also follow these instructions to get the job done.

  • Apply corrosion-resistant coatings on metal components.
  • Replace worn-out parts, such as belts and bearings.

However, all these fixes will mean nothing if you fail to do regular checks for any signs of wear and tear. Other than that, you also have to ensure timely replacements of refrigerants to prevent chemical breakdown and maintain optimal system performance.

Problem #09: Rust-Related Problems

When it comes to your RV’s air conditioner, it’s essential to protect it from getting wet for too long. If you leave your RV parked without any shelter in rainy weather, it can start to get rusty. Skipping maintenance checks can give rust a chance to take hold and cause problems. You should especially observe caution when:

  • RV has an older AC unit, which is prone to rusting.
  • Continuous exposure to rainy weather.
  • Moist conditions.

In all such situations, you have to be extra careful and take precautionary measures.

Solution

Rusting can especially prove to be problematic for fans. So, if the fan is stuck due to rust, try turning it by hand. Afterward, apply a lubricant such as WD40 to prevent future sticking. I recommend you follow these easy solutions and preventive measures to avoid future rusting issues.

  • For minor surface rust, use a wire brush to remove it.
  • Keep your AC well-sealed to minimize contact with moisture.
  • When the unit is not in use, cover it to shield it from moisture and prevent rust formation.

Once the rust is gone, apply rust-resistant paint to create a protective layer. If crucial components like the motor or fan blades are significantly rusted, consider replacing them.

Problem #10: Condensors Freezing Up

I have also experienced a peculiar problem that may be a reason for your AC unit causing the humming sound. If you run the air conditioner non-stop, especially in cool weather, it can also cause freezing. Several other factors can lead to internal freezing.

  • Dirty filters block airflow.
  • Ice buildup on the condenser coils.
  • Low refrigerant can make the AC work too hard, leading to freezing.
Solution

It is not a common issue, especially in hot and sunny weather. However, you can face this issue on cold winter nights. You can apply these tried and tested fixes as I did when I faced the air conditioner freezing up issues once in December chilly weather.

  • If you suspect your AC is frozen, turn it off and let it thaw completely.
  • Check refrigerant levels and refill if low.
  • Regularly inspect and clean or replace air filters.

Moreover, if you want to avoid the condenser freezing issues, expose the coils and let the ice melt by opening the AC vent.

For further understanding, I would recommend you check out this visual guide.

Preventive Measures to Avoid Humming and Non-Operation of RV AC Units

I have been using the RV for ages and faced all the issues expressed above on one occasion or the other. With my experience throughout these years, I have made a list of all the tips to ensure the air conditioning system can function seamlessly. All these suggestions will keep your AC free from undesirable humming or interruptions in the fan’s operation.

  • Keep the AC unit clean and debris-free to prevent drain and fan clogs.
  • Periodically check wiring condition and promptly address any faults.
  • Ensure condenser coils are unfrozen for optimal functioning.
  • Cover the AC during RV inactivity to protect it from external elements.
  • Apply mechanical oil to lubricate the fan for smooth operation.
  • Regularly lubricate the fan to prevent friction-related problems.

How to Differentiate Sounds Coming from AC Unit from Humming?

Differentiating how we describe sounds from professional assessments can be challenging, especially when it comes to air conditioning units. Here are potential meanings for various sounds that will help you identify the real problem in your air conditioner.

How to Differentiate Sounds Coming from AC Unit from Humming?
  • Buzz: If you hear buzzing instead of humming, it often indicates an electrical issue.
  • Clicking: A clicking noise might be related to the air conditioner’s relays and warrants inspection.
  • Rattle: A rattle suggests something is loose, whether it’s a detached part or foreign debris.
  • Banging: If your RV air conditioner produces a banging sound, there may be a loose part or a system imbalance.
  • Squealing: A squealing noise could indicate a failing fan motor.
  • Screeching: This loud warning indicates a serious issue demanding immediate attention.

Overview Of People’s Experience With RV AC Humming

I have observed that AC humming sound is a common problem faced by many RV owners. After going through many reviews and complaints online, I have selected some to give you more in-depth information related to this issue.

<strong>Razzman</strong>

Razzman expressed his concern related to intermittent issues after accidentally tripping the breaker during a recent trip. Then, he experienced a persistent hum when attempting to turn on the A/C with no actual function. “He recommends replacing the thermostat as a potential solution”.

<strong>Garry</strong>

Garry shared his experience related to a minor issue like debris in the external fan blades. “He recommended removing the shroud on the roof and manually turning the fan blades while the A/C is off to avoid any sudden movements“.

<strong>Jennie K</strong>

Jennie K explained that a hum indicates either a locked-up fan or a running compressor with a non-functioning fan. To diagnose this issue, “she suggests that an electrical meter is necessary to understand the issue“.

FAQs

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

Yes, a low level of coolant in an RV AC unit can lead to humming. The low coolant can strain the compressor, causing it to hum as it struggles to operate efficiently.

How do you know if an RV AC capacitor is faulty?

If a capacitor is faulty, the RV AC may exhibit issues like difficulty starting, humming without proper function, or weak airflow. You can use a multimeter to check capacitance for confirmation.

What can I do to prevent my RV AC unit from humming but the fan not running in the future?

You can prevent this particular issue by regularly cleaning air filters and coils to maintain optimal performance. Also, you must ensure a stable power source to prevent electrical issues. In addition, confirm thermostat settings for the right temperature and mode.

Conclusion

In the end, when you see an RV AC unit humming but fan not running, there could be various reasons behind it. Some of these include blockage in the fan, malfunction of the control board, or tripped breakers.

To overcome these issues, regularly clean the AC unit and eliminate any repellents. Also, inspect the panel, replace the damaged control board, and check for any blown fuses. In case, you are unable to resolve the issue, immediately consult a professional.

Have you ever felt any humming sounds from your RV AC unit while the fan is off? Well, share your experience with me in the comment section below!

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