what to do when ac blows a fuse

Here Is What To Do When Your AC Blows A Fuse

When your AC blows a fuse regularly, it can be concerning, to say the least.

Not only can an electrical shock permanently damage your air conditioner, but it can also lead to the destruction of property, and in the worst-case scenario, the loss of lives. 

Therefore, we’d like to advise you earlier on to always be on the lookout for AC electrical problems (especially if your system and wiring is a few years old).  You would never know how long your AC units last in Arizona so it’s important to get it checked out ASAP.

So what should you do when your AC blows a fuse?

The first thing you have to acknowledge is the fact that your air conditioner can’t blow a fuse on its own- There has to be a reason why. 

Therefore, not only should you be replacing the blown fuse, but you should also do repairs to make sure it doesn’t happen again. 

We’ve dealt with many clients who keep on wondering why their AC fuse keeps blowing up. Little do they know that blown AC fuses are usually signs of underlying problems. 

Don’t worry, blown fuses are fairly common air conditioner problems. 

Now, of course, some homes are modern and have panel breakers instead of fuses. However, the result is still the same. 

Your panel breaker will keep on tripping until you fix your air conditioner’s electrical faults.  

Before we get started, you need to know what a fuse is and how it works in an air conditioner. 

What is an AC fuse?

A series of fuses, used to represent the concept of "AC blows a fuse."

The fuse is a wire inside a glass casing, found in the disconnection box connected to your AC. 

The fuse is a protective measure meant to protect your air conditioner from electrical damage. 

In case there is an electrical overload, the fuse sacrifices itself and is blown up to break the circuit and protect your air conditioner. 

Why would there be an electrical overload? It usually happens during the very hot summers when your air conditioner is pushed to its limits. To cool more air, the AC ends up drawing more power than it can handle.

Power surges can also cause electrical overload. 

How to check for a blown AC fuse

How will I know if my AC fuse is blown? 

You can start by listening to any weird air conditioner noises- Anything out of the ordinary that might cause you to raise an eyebrow. 

In particular, be on the lookout for buzzing, humming, or clicking noises. 

You might be wondering, “Why and how is there a humming sound if the fuse is blown?” 

The humming sound is produced by the running furnace that is still trying to convince your air conditioner to turn on.

Besides sound, you can further investigate and confirm whether or not your AC fuse is blown. 

Now, we’re not advising you to be adventurous. You should only investigate further if you have the basic knowledge of air conditioner circuits.

If not (of which many of you don’t), you’re better off calling in an HVAC professional to do the job for you. Remember, it only takes one mistake (a split second) to cause an electrical disaster. 

We’ve got you covered. We’re the best air conditioner specialists in Phoenix

Use a voltmeter to check for blown fuses

Below are the steps you should follow.

  • Start by first locating the air conditioner’s fuse. As mentioned earlier, it’s in the disconnection box. The box is usually grey and right next to your outdoor unit. 
  • Open the disconnection box to expose the cables inside. Be careful- We are now in “high voltage” territory. 
  • Turn on your voltmeter and make sure the reading is zero. 
  • Start by testing the lines that bring in electrical power to the AC (in lines). The reading should be around 220 to 240 volts- This proves there is no problem with the power supply. 
  • Next, test the outgoing lines. If the reading is zero, then your AC fuse is blown. 

If you don’t have a voltmeter, the only way you can check if your AC fuse is blown is by replacing it with a new one of the same capacity. If the new one works, then the old one had blown up. 

How to remove and replace AC fuses

You’ve confirmed that your air conditioner’s fuse is busted and needs replacement. Honestly, we’d advise you to invite over a professional to do the dirty work for you. 

However, if you still insist, below are steps to follow. 

  • First, for maximum security, shut down the breaker to cut off your air conditioner’s power supply.
  • Next, locate the disconnection box. The fuse might be in the disconnection box together with the wires. In some cases, it’s in the “T” handle. 
  • Pull the handle to stop the current from flowing into the fuse.
  • Use a pair of pliers with plastic insulation to remove the fuse. 
  • Stick in the new fuse and assemble the disconnection box. Make sure to leave it as you found it. 

What fuse type should I use for my AC?

You need to be very careful when buying a new fuse for your air conditioner. The new fuse has to be compatible with your unit’s power requirement.

How will you know what fuse rating to go for?

Start by taking a look at the blown fuse- The rating is usually written on the fuse. 

If not, then you can look for it in your unit’s access panel (that plastic cover with your unit’s model and many other details) or the manufacturer’s guide. 

In case you don’t find the fuse rating on the access panel or manufacturer’s guide, then we’d advise you to stop what you’re doing and call in an air conditioner specialist. 

You can permanently damage your air conditioner if you end up using the wrong fuse. 

A fuse with a higher rating will allow a lot of current to reach your unit. Too much current will fry your air conditioner. Trust us, we’ve seen it happen before. 

Why does my AC keep blowing fuses?- The 5 reasons why

1. A clogged motor

A clogged motor means the entire system isn’t working as smoothly as it should. And as a result, the AC will have to draw more power- This, in turn, damages your AC capacitors, and more current is allowed into the circuit. 

The fuse then blows up as a last resort to save your air conditioner. 

2. Clogged filters

Clogged filters mean that your air conditioner’s airflow is restricted. As a result, more power will be required, which ends up frying the fuse. 

3. Dirty condenser coils

Dirty or “insulated” condenser coils means they’re not able to lose heat as efficiently as they normally would. Once again, your air conditioner is forced to draw in excess power to be able to “force out” more heat. 

4. Condenser shuttering

Sometimes, especially under extremely hot weather, your compressor might malfunction in that case AC keeps turning on and off. The power fluctuation will cause the fuse wire to wear and tear, and finally blow up. 

5. General circuit problems

You’ve noticed that even after solving all the problems above, your AC’s fuse still keeps on blowing up. 

It’s time you called in an HVAC professional to thoroughly check your air conditioner’s electrical circuit and wiring. 


Nothing is as annoying as an air conditioner fuse that keeps blowing up every other week. Fortunately, you now know what is causing it and what to do about it. For more of our content, you can read the next articles “Different Types of Hot Water Tanks” and “How to Remove Nitrates from Well Water“.

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