Ever been enjoying a nice, cool summer day when all of a sudden you realize – “why is my air conditioner buzzing when off”? It’s more common than you think!
Here, we’ll talk about the possible causes and what we recommend you do about them.
Some reasons why your AC is buzzing when off include:
- Your AC unit is frozen
- Parts are loose inside your AC
- You have electrical issues
- AC is unbalanced
- Condenser fan is broken
Below you’ll find out how to fix these issues and if you need to call a technician or not.
Let’s get started.
5 Reasons Your Air Conditioner Is Buzzing When Off
1. Your Unit Is Frozen
One of the main reasons people experience a buzzing air conditioner is a frozen unit.
Since the machine is making cold air, when you run it for a long while at a time, it can start to freeze up.
This can also happen if the airflow within the machine is restricted or your refrigerant is leaking.
Regardless of the reason, you can know for sure that this is the cause of the loud buzzing if you also see ice on the unit.
2. Parts Are Loose Inside Your Unit
Air conditioners have a whole lot of different parts that make them go at any point, and over time, some of them are bound to come loose.
When they do, they can make this buzzing sound.
Loose parts can also cause uneven wear and tear throughout your unit, so you should certainly try to get them repaired if they are the cause of the buzzing.
3. There Are Electrical Issues at Play
There are a couple of different kinds of electrical issues that can contribute to a rattling noise.
Most commonly, this is due to the contactor relay switch – a low-voltage switch located on the exterior of your unit that controls how electricity accesses the compressor.
That isn’t the only electrical issue that can cause this humming noise – there are several smaller, less common ones that can still be both annoying to deal with and reduce your unit’s effectiveness.
No matter what the problem is, if it’s electrical, you should get professional help.
4. Your Unit Is Unbalanced
The compressor that sits at the base of your air conditioner supports it on rubber feet.
Over time, these feet can wear down from the pressure of weather and the continually operating air conditioning unit.
When this happens, the unit can become unbalanced, causing the buzzing issue.
5. Your Condenser Fan Isn’t Working
Every air conditioning unit has a condenser fan, which works to blow in air from the outside of the unit.
If the motor for your condenser fan is damaged, this might cause operational failure.
It could also cause a malfunctioning compressor, which would leave the unit without the ability to cool and pressurize the refrigerant.
Compressor failure might also cause problems for the voltage, leaving it poorly regulated and potentially flowing through your air conditioner at the wrong amperage.
The buzzing comes about when the internal blower is working properly, but the fan isn’t turning.
This can happen in a variety of cases, including when the debris is impeding the fan or when there is a mechanical failure within the fan itself.
How to Stop Your Air Conditioner from Buzzing
1. First, Try Thawing the Unit
Even if you don’t see ice on the unit, it still might still be frozen within.
Turn off your AC unit and allow it to thaw for several hours. If there is still a problem when you restart it, the problem is likely not connected to freezing in your unit.
2. Stabilize the Unit
If you observe that your unit is unbalanced at its rubber feet, you can try stabilizing it yourself as an interim solution until you can get a technician to find a more permanent solution.
Small pieces of precisely-measured wood can work well for this.
3. Replace the Contactor Relay Switch
We do not recommend trying to replace the contactor relay switch without help from a technician. But if you want to try, here’s how you would go about it:
First, shut off both the power for the air conditioner and the furnace/air handler. It is vital that you do this step – you are putting yourself in serious danger if you operate on the wiring here with the power on.
Once you have powered it off, verify that you have done so with a multimeter. Again, you really don’t want to start operating on it if you’re wrong.
Then, mark all the wires that connect the contactor to the unit.
Mark both the wires and where they’re located on the contactor. Once you have done so, you can begin the process of removing the contactor itself – starting with the wires and following with the mounting screws.
After completing that, you can mount your new replacement contactor. When you reconnect the wires (using your previous wire marks to guide you), make sure that the wire connections are nice and tight.
Finally, turn the unit and the furnace/air handler back on and observe it through a full cooling cycle to make sure nothing has gone wrong.
Is My Air Conditioner Buzzing a Sign I Should Call an HVAC Technician?
You should first try thawing the unit as discussed above. If that does not work, then you should certainly call an HVAC technician.
All of the potential reasons for your air conditioner to be buzzing while off can cause performance issues, and some of them are dangerous to try and fix on your own.
The good news is, you can hit the button below and talk to a local, certified HVAC technician that will fix your problem in a jiffy.
There you have it – if your air conditioner is making a buzzing noise while off, it’s likely that your problem is one of the ones identified in this article.
No matter how you decide to proceed, it’s important that you do something: these problems, if you let them continue, can prove destructive to your machine (and your energy bill!) in the long run.