AC Unit Making Noise After Power Outage

7 Reasons Why Your AC Unit Making Noise After Power Outage!


A power outrage can cause many of your devices to malfunction or take damage. Your AC is one of the very likely electronics to get affected and make unusual noises.

So, why is your ac unit making noise after power outrage?

Your ac can make noise after a power outage if your AC’s fan is too old and you might need to replace it. Also, the coil may become frozen due to a lack of airflow. That’s why a clogged air filter needs to be cleaned.  Moreover, there can be issues with your thermostat and condenser as well.

Does this seem to address your problem with the noise? There are other reasons that can be responsible too. Lucky for you, I’ve figured out all the ways to troubleshoot it. 

So carry on to know how to fix these problems effectively!

7 Ways to Fix Your AC Unit Noise after Power Outrage!

Can a power outage damage an ac unit? Yes, a power outage can damage your AC or Furnace. It can cause issues to any devices that use electricity in fact. 

Here are 8 reasons why your AC unit might make noise after there is a power outrage. We’ve also come up with ways of fixing it. So have a look!

Reason 1: The Unit’s Fan is Old

It is important to replace your unit’s fan when it fails to work properly. The older the AC unit, the more likely it is to make noise. This noise can be caused by loose or broken fan blades or some loose parts.

Source: YouTube

If the parts are loose then it often indicates a substantial amount of wear in the joining parts. Also, the sudden stop-motion due to power outrage will also put stress on the joints. Eventually, this wear will make the joints loose and result in unusual noises.


First, check if the AC fan is spinning properly or if the bolts are fastened tightly. If the blades or any parts are loose then use a screwdriver to tighten them properly.

But if you notice any parts that are broken then you may need to replace the fan. In this case, there will be some compatibility issues so it’s better to not attach any fans to your AC. I would suggest you contact your AC service center and let them handle the issue

Reason 2:  The Unit Has a Frozen Coil

This can happen if you have had a power outage for more than 36 hours. There is a good chance that your fan will freeze. This can cause an explosion of air and possibly make noise. If your AC’s coil is frozen you might as well find that your liquid line is cold.  

Also, another core reason behind this issue is a clogged air filter. Dirty air filters or malfunctioned ducts can cause weak airflow. This eventually prevents your equipment to work and keep the coil warm.

Source: Home Stratosphere


Make sure the air filter is fresh and clean to solve the problem. Airflow is restricted by clogged air filters. This clogged air filter is a major issue behind the AC blower not working after a power outage.

Follow this visual guide to clean your AC filter properly.

If the condition of your filter is too bad then you might need to replace them. Filtrete AC Furnace Air Filter and Simply by MervFilters Air Filter are great replacement air filters. However, while buying a replacement air filter make sure it’s compatible with your ac.

Reason 3: The Thermostat is Not Set Properly

You can find your AC thermostat not working after a power outage. This can happen if your thermostat is not set to the proper temperature.

The temperature inside your home will differ from what the unit thinks it should be. This brings about the unit to run longer than usual. And it’s done causing the outside ac unit to make a loud noise


It’s possible that cleaning the interior of your thermostat will solve the problem. The sensor will have problems operating properly if there is too much dust within. If the problem persists after cleaning, your sensor may need to be recalibrated.

Reason 4: A Broken Thermostat

The thermostat is the most common culprit that causes noisy AC. A broken thermostat can cause the unit to constantly stay on. And so it makes a lot of noise as it will struggle to turn it off once there’s a power outage.


If cleaning up or tightening the thermostat’s connections does not solve the problem, consider swapping it. 

Source: CNET

Switching to a smart digital thermostat is recommended. Digital thermostats improve the comfort of your house. While also lowering your heating and cooling expenditures. I would recommend you to get the Google Nest Learning Thermostat

However, if you don’t wanna get that one no worries! There are a lot of options for you to choose from.

Ecobee3 Lite SmartThermostat, BlackCheck Deals on Amazon
Honeywell Home Home RTH6360D1002 ThermostatCheck Deals on Amazon
Google Nest Thermostat – Smart Thermostat Check Deals on Amazon

Reason 5: The Condenser is Dirty

When an AC is filthy and dusty, it can make a lot of noise. Keeping a unit clean will help prevent this type of problem from happening. Here’s an example of a dirty ac condenser that you might think is okay.

But let me tell you that even this amount of dust or dirt needs to be cleaned properly.


So to solve this, you simply have to clean the condenser. Here’s how to clean a dirty ac condenser

  • Pull the plug connector in the power box or turn off the AC breaker switch in your main breaker panel to disconnect the power at the AC condenser.
  • Now remove the screws using a cordless drill or a screwdriver.
  • Remove the panels one after the other, starting from the rear side of the unit. Make sure you don’t damage the condenser fins. If the fins are bent then straighten those bent fins.
  • Finally, clean the fins by using a soft-bristle brush or a hose with a spray nozzle.

After you’re done ensure that the whole thing is screwed back properly.

Reason 6: The Fan has been Obstructed

An obstruction in the cooling fins that force air out might cause friction. And therefore, you get noises in your AC unit.


Check your filter to see if it’s clogged with dust and debris. Turn off the AC, unplug it, and clean the cooling fins for any obstruction. 

Next, plug in the power cord and turn on the unit to avoid a short circuit. Clean any dust that might have collected on top of or inside of your AC unit.

Reason 7: A Broken Condenser Fan Blade

A broken blade in a condenser fan can cause similar problems as well. The blades are also responsible for pumping cool air out of the unit. Which will not be efficient if they are broken or damaged. Causing them to make unwanted noise.


You might be able to use decent glue to repair the current blade. Or you may as well use a two-part epoxy. However, it’s only if the fracture or chip is little. Here are some of our recommendations for a suitable adhesive for this application-

J-B Weld 8237 PlasticWeld Plastic Repair Epoxy PuttyBuy Now!
Gorilla Super Glue GelBuy Now!
Loctite 681925 Super Glue Plastics Bonding SystemBuy Now!

However, if it’s rusted or broken, though, you’ll need to replace it. One that is the same size and design as the others are required.

After a power outage, you might find various other problems with your AC unit. You might find that your blower motor can’t draw enough amperage. Well, fixing these issues might be difficult as fixing low-pressure lockout issues. 

However, there are times when it would be better to call an expert. Since he could service your system more quickly and efficiently.


Should I switch off the air conditioner if the power goes out?

Turn off your air conditioner if you lose electricity. The reason for this is simple. You don’t want your air conditioner to overload the circuit when the power comes back on.

Can a compressor be damaged by a power outage?

A powerful electrical incident can destroy the windings that supply the compressor’s start and run functionality. This can lead to compressor failure sooner than expected.

Is the outdoor AC unit protected by a breaker?

There are two breakers on your air conditioner. The exterior unit is controlled by one, while the internal unit is controlled by the other. If the breakers appear to be tripped, reset them by turning them off and on again.


We hope now you know what’s causing your ac unit making noise after a power outage. Whatever the reason or reasons are, you can surely get rid of it following our instructions. 

It’s always better to keep your AC unit checked once every winter. 

All the best wishes!

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