RV AC Hums But Won’t Turn On (Why and How To Fix It)

When you return from a very hot day of activities, the first thing you want to do is turn on the air conditioner and cool off. However, your AC unit has other plans and only hums when you turn it on. It is not a fun sound to hear when all you want to do is cool off and get ready for the evening.

There are many sources for this problem and the first place to check would be your voltage. If your AC unit is not receiving enough voltage it won’t have the power to turn on and all you will hear is a humming sound. Check your power input to see if this is the source, if not, you will have to keep searching.

To learn more about this topic, just continue to read our article. It looks into the topic and provides you with the information you need to find the source quickly. Once you find it, you should be able to make the repair just as fast.

Why is My AC Unit Humming And Not Turning On?


The good news in this situation is that you know it is an electrical problem. The bad news is that there is more than one electrical issue that can be the source of the humming.

1. Start capacitor- these little parts can fail often. If you are looking for a silver lining here, then you can find these parts cheap and replace them in a few minutes. The key will be to mark where the wires go so you do not make any mistakes in reconnecting those wires.

2. Control board- another key component that can interfere with voltage delivery. This part may be a bit more expensive than a start capacitor and may need a technician to make the replacement.

3. Faulty compressor- if you have replaced the start capacitor and still get a humming sound, then chances are your compressor is bad and needs to be replaced. This replacement is not just the compressor but the whole AC unit.

4. Fan motor- this could get stuck and in need of lubrication. Turn the power off and try to spin the fan motor by hand. This will tell you if you do need some lubrication to the area or you could break the motor free from whatever is binding it.

5. Loose or faulty connections- check the wiring and all connections to make sure nothing is loose or broken. You will have to turn the power off to do this work. Loose wiring or faulty connections stop the voltage from getting through to where it is supposed to go and nothing has the power to work.

RV AC Hums But Won't Turn On


Here are a couple of more possible sources that have not been discussed yet. The first is that you probably have not cleaned your AC unit for years. As technology improves on AC performance and energy efficiency, dirt build-up is something technology has not overcome yet.

If your AC unit is very dirty, your modern AC unit will not function. This cleaning is not just limited to filter cleaning or replacement. It is a thorough cleaning that gets rid of the dirt on evaporators, compressors, coils, and other components.

The second other possible source will be your AC unit is low on coolant. It happens even with the best RV AC brands. You need to check the coolant level in your specific unit and then get a technician to replenish the supply. This is not a repair you can do yourself.

THE RV AC Unit is Humming But The Fan Not Running


The most common-sense answer to this would be that there is a problem with the fan motor. It could be dirty, had its wiring joggled loose from road vibration or the fan motor has gone bad.

You would need to check for dirt first, then the wire connections to see if those easy-to-fix options are the culprits. Do some cleaning and tightening or replacing of wires and see if that solves the problem.

If not, then get your multimeter and test the fan motor. The multimeter will let you know if the motor is working or not and if it isn’t then replacement will be your only fix.

Other possible locations and parts to check include the following list:

- 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

AC Repair Or Replacement?

This is often a tough question to answer. Generally, the age of your AC unit will be the biggest determiner. If your unit is under 10 years old, it is often better to repair what is wrong and get more life out of your AC unit.

However, if your AC unit is over 10 years old, then it may be better and cheaper to replace it with a more modern version. Not only can you save on the high repair costs, that is if parts are still made for it, but you can also save with the efficiency of the upgraded version.

While buying new seems to be more expensive, it is not more expensive if you have a hard time finding parts for your current unit and then have it break down soon after it is repaired. Sometimes replacement is the best way to go.

Some Additional Words

When you need cold air after a very hot day outside, nothing seems to be worse than the AC unit humming but not turning on. If you are not an electrician, it is best to call in a technician to handle the diagnosis and repair.

As you have read, there are many sources that can cause this problem from easy to fix to very complicated to repair. It is best to let the technicians handle the work for you.

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