AC Breaker Keeps Tripping Breaker: 9 Common Culprits & Fixes

“My AC keeps tripping the breaker. What’s wrong? How do I stop my AC from tripping the breaker?”

AC tripping the breaker is annoying. Even more troublesome, repeatedly trying to run an air conditioner that keeps tripping the breaker can result in permanent damage to the AC unit. So, easy on the breaker reset button; you should diagnose and fix the problem first.

ac keeps tripping breaker
It’s very unlikely that repeatedly pressing the breaker reset button will cause a fire. However, damage to your AC unit can be in $1,000s if you don’t fix the AC breaker problem.

Here is what might be happening with your air conditioner:

  • Air conditioner trips the breaker immediately. When you turn the AC unit, the breaker will flip immediately or only after a few seconds.
  • AC trips breaker after 5 minutes or so. The AC starts OK, but after a few minutes, the breaker will trip. This, for example, is typical for the AC compressor tripping breaker (outside AC unit tripping breaker).
  • AC trips breaker after a few hours. An air conditioner will work fine for several hours before it trips the breaker.

To help everybody out, we are going to look at how to check why the AC unit keeps tripping the breaker. We are going to check for 9 key culprits that cause the AC circuit breaker to keep tripping.

There are only two roots for why your AC keeps tripping:

  1. You have a faulty breaker. This involves issues with circuit breaker, AC wiring, and electrical short circuits.
  2. You have a faulty air conditioner. This involves issues with the AC compressor, condenser unit, capacitors, air filters, fan motor, low refrigerant levels, and even frozen AC unit. The primary cause is AC overheating due to limited airflow or a faulty part.
    sketch of air conditioner for fixing ac breaker that keeps tripping
    Sketch of a standard mini split. Most problems that cause the amp spike (and therefore the breaker to trip) originate from the outdoor unit (compressor issues).

As every HVAC professional does, you should check these culprits one by one, eliminating the causes as you go. Once you have correctly detected what is causing the AC breaker to keep tripping and fix the problem, your AC unit should work smoothly again.

Note: For every culprit, we are going to tell you if it causes the AC breaker to trip immediately, after a few minutes, or after a few hours, and explain why.

Here are the most common culprits (listed one by one) for any air conditioner type – be it central air, mini split, portable, or window air conditioner – to keep tripping the breaker. We are going to start with breaker-related issues (#1 to #3) and continue with AC unit-related issues (#4 to #9):

#1 Circuit Breaker Is Bad, Loose, Or Undersized (Causing AC To Trip Breaker Immediately)

If you are lucky, the AC breaker keeps tripping due to a bad breaker. This is one of the easiest problems to solve; problems with the AC unit itself are harder and costlier to fix.

It’s not uncommon to see a bad circuit breaker. Both new and old breakers can go bad due to wear-and-tear or acute amp surge that fries the breaker. Over time, even well-installed circuit breakers can come loose and cause all sorts of issues, including tripping unexpectedly.

reset button for ac breaker
Make sure that AC breakers are fixed (not loose).

In limited cases, we also see that homeowners have installed a circuit breaker that is just too small. Example: A 3-ton AC unit on 220V has a max. wattage of about 3,600 watts and requires a 25A or 30A breaker. You can check what size AC breaker you need here accounting for NEC 80% ampacity rule.

Dead giveaways of a bad breaker are:

  • Breaker smells like something is burning.
  • Breaker is hot to the touch.
  • Breaker keeps tripping all the time.

Solution: First, you need to check if you have a bad breaker. Secondly, check if the breaker is loose; try to nudge it from left to right to set it back in the required position. Of course, you will also have to check the above article if indeed your breaker is big enough to handle all the amps that you need to run your AC unit.

If you have a bad breaker, you just simply replace it. Get a new one – circuit breakers are quite inexpensive – and be sure to check that it has the same ampacity as the old one. Everybody can DIY breaker replacement; you can consult this guide on how to replace a circuit breaker if you need some help.

Once you have a working breaker again, your AC should stop tripping it.

#2 Wrong AC Wiring (New Air Conditioners Trip Breaker Immediately)

Another possibility, especially for new air conditioners, is wrong wiring. If you have a newly wired thermostat or you have just replaced an old thermostat, chances are that not all wires are connected to the right sockets.

For air conditioners, you will have to connect:

  • Blue or yellow wire is meant for cooling. These wires are connected to the Y terminal in a standard thermostat.
  • Red fire for power, connected to R.
  • Common wire (usually black) connected to C.
wrong thermostat wiring leading to ac breaker tripping
Example of a correctly wired air conditioner (this is a 5-wire Honeywell thermostat).

For more advice on how to wire a thermostat, you can consult the thermostat wiring guide here.

Wrong wiring will lead to the outside AC unit tripping breaker immediately (central aircon or mini splits). This is a standard AC compressor tripping issue; the compressor creates a surge of amps that can hit an undersized breaker if it’s wrongly wired.

Solution: Check that all the wires are in the right sockets. In limited cases, you will have to can an electrician to fix this, but most people can use the guide cited above to adequately wire a thermostat themselves.

#3 Electrical Short Circuit (Unsheathed Wires Touching)

Any short circuit can cause a spike in electrical current (amps) that will trip the breaker. In fact, one of the reasons why we use circuit breakers in the first place is to protect our circuits against short circuits.

In the case of wiring air conditioners, the short circuit happens when two exposed wired (unsheathed because the coating has been degrading for years) touch.

Example: Let’s say that the blue and red wire touch. This doesn’t happen if they are properly insulated. However, over time, insulation can decay. When this happens, the electrical current from two wires will travel along a single wire (the one with the least electric resistance, according to Ohm’s law). This will cause a spike in amps that can knock out the breaker.

amp spike causing ac fuse to trip
If you were to measure the electric current during a short circuit, you would see a surge of amps. Example: Breaker can handle 20A but short circuit produces 30A spike, flipping the breaker.

Admittedly, it’s very difficult to tell if you are experiencing a short circuit. You do have to go to check all the wires to see if the insulation is damaged. This short circuit problem also causes the AC to trip break immediately, after 5 minutes, or even after 10 hours of running the AC unit. It is not time-specific which makes the detection even harder.

Solution: If you suspect that your AC unit tripping the breaker due to a short circuit, you can check the wires yourself or call an electrician. Once you find faulty wires that are causing the short circuit, you have to reapply the coating, or, in more cases, just replace the wire.

All of this, of course, is easier said than done.

Once you have eliminated the thermostat-related problems, you can start checking if there is something wrong with your air conditioner unit, resulting in the breaker tripping repeatedly:

#4 Dirty Condenser Coils (Causing Outside Air Conditioner Circuit Breaker To Trip)

A lot of AC tripping breaker problems are caused by the air conditioner overheating. One of the most common examples of this is the air conditioner circuit breakers outside to trip.

The outdoor condenser coils are exposed to the environment. That means that anything from dirt, leaves, dust, and grass, can find its way into the AC outdoor unit (you may even find a dead rat in there). If this dirt accumulates on the fairly exposed condenser coils, you will have problems with the outdoor AC unit tripping breaker.

dirty ac coils tripping breaker
Example of what dirty outdoor coils (you may even see brownish ice formation) looks like.

These condenser coils are basically superb heat exchangers. They expel all the heat that is generated in the refrigeration cycle. If these condenser coils are coated with dirt, for example, their ability to conduct heat is impeded. Obviously, if the coils can’t give away enough heat, the whole outdoor unit will get overheated.

And overheating leads to the AC tripping the breaker.

In this case, the AC breaker won’t turn trip immediately. It won’t even trip in 5 minutes or so. Dirty condenser coils are one of the most common reasons why the AC trips breaker after a few hours. The AC will overheat in time and that can take anywhere from some 10 minutes to several hours.

Solution: Clean the outdoor condenser coils. Open the outdoor unit and check if there is dirt coating on the coils. If there is, clean out the debris and spray them with detergent or coil cleaners. You can read how to clean the condenser coils on the Carrier website here.

After the outdoor coils are cleaned, they can adequately exchange heat again. That means that all the heat that has to be expelled via the coils will be released into the atmosphere again. As a result of the AC unit not overheating, you will no longer have a problem with AC breaker tripping.

#5 Dirty Air Filters (Restricted Airflow Results In Overheating And Trips Breaker)

Dirty air filters are another common culprit for an AC unit to trip breaker after a few hours.

We all know that every AC should have adequate airflow. If the filters are dirty, they restrict the airflow. This can cause a series of unwanted issues and will eventually lead to AC overheating. And, as we know, if the AC is overheating, it will inevitably trip a circuit breaker.

Everybody pretty much knows what to do with dirty air filters, right?

Solution: Clean or replace the air filters. This will again enable the AC unit to operate at sufficient airflow. The AC unit will not overheat. The AC breaker will not trip. It’s a pretty simple fix.

#6 Compressor Fails To Start (Or Hard-Starting Compressor)

Out of all the things that may go wrong, the compressor-related issues are the worst. When you have a faulty compressor, you will in almost all cases have to replace it. This replacement can be so costly that homeowners with older units usually just replace the whole air conditioning system.

Now, if you have a faulty compressor (the reason might also be a fault capacitor), you can expect two things to happen:

  1. Compressor doesn’t start at all. Regardless of this, the AC compressor can still trip the breaker. You will notice that in this case, the AC compressor trips the breaker immediately.
  2. Compressor starts slowly (usually takes a few seconds). This is an indication of a faulty compressor and might lead to the AC compressor tripping the breaker after a few minutes.

The compressor – the main part of the AC – is responsible for compressing the refrigerant gas. If it doesn’t do its job, the AC unit might start overheating and blowing warm (instead of cold) air.

When the compressor doesn’t start at all, there is usually a spike in amps along the compressor wire to the breaker. This will trip the breaker immediately.

If you have a hard-starting compressor, the breaker won’t trip immediately. Nonetheless, such a compressor repeatedly can repeatedly send amp spikes towards the breaker in order to keep running. Eventually – usually in a few minutes or so – one of these amp spikes will overwhelm the circuit breaker and the breaker will flip.

Solution: This is a hard pill to swallow but you will probably have to replace the AC compressor. This is a complex replacement process you can’t do yourself; you will require an HVAC professional to do it for you.

You can, of course, take this ‘opportunity’ to replace the AC unit altogether. If your AC unit is past its prime (15+ years old), replacing the whole air conditioner makes sense in many cases.

#7 Compressor Is Grounded (Wires Touching The Sides)

Another problem a compressor might have – much less troublesome – is some wire displacements. Namely, the electrical wires that power the compressor are unsheathed and touching the compressor casing. It’s always best to check if everything is OK with the compressor wires.

Of course, if the wires touch the metal casing, all that electricity will go to the ground (we talk about the compressor being grounded). Inevitably, this will cause a spike in amps that will knock out the breaker.

Now, this may happen when you turn on the AC, after a few minutes, or even after several hours. The vibrations in the compressor pretty much displace one wire so much that it touches the casing, and that may happen immediately or even after some hours.

Solution: Check if all the wires that go in and out of the compressor still have their insulation coating on them. Also, check if the wires are neatly packed and away from the casing. If you find an exposed wire close to the casing, it’s very likely this is the wire that keeps tripping the AC breaker.

Use a plastic or nylon line to fix the wire in place, away from the casing. You can even replace that wire if you see that the insulation coating is severely damaged. After you do that, your breaker should stop tripping.

#8 Low Refrigerant Levels (Lines Leaking Freon)

All air conditioners work based on the refrigerant cycle. For this cycle to work properly, the lines have to be full of freon (refrigerant gas like R22, R410A, and so on). If you have a leak in the refrigerant lines, there will be less refrigerant within the lines which will lead to AC overheating and potentially tripping the breaker.

Example: If your window AC keeps tripping the breaker, the refrigerant leak could be the culprit.

Solution: You have to check if the refrigerant levels are indeed low by measuring the refrigerant pressure. If freon is indeed leaking out, you will first have to seal the leak and then recharge the AC unit.

In most cases, you will need professional help for this.

hvac professional measuring refrigerant pressure
HVAC professional measuring the refrigerant pressure in the refrigerant lines.

If you want to know how a professional refills the freon, you can consult this article about how to recharge a window air conditioner.

#9 Faulty Fan Motor (Leading To Overheating And Breaker Tripping)

In limited cases, we also see that a faulty fan motor is responsible for the outdoor AC unit tripping a breaker after a few hours.

The outdoor fan produces airflow that expels the heat into the environment (cooling the condenser coils). That fan is powered by the motor. If the motor doesn’t produce adequate power output, the fan doesn’t produce adequate airflow, and the outdoor AC cooling process is impeded.

bad fan motor causing air conditioner to trip breaker
This is a fan motor that powers the fan (via the belt) in the outdoor unit.

This can lead to AC overheating and tripping the AC breaker. This happens when the AC is overheated enough; it takes a few hours (not on start-up or after a few minutes).

Solution: Check if the outdoor fan is spinning. If not, the problem might be a faulty fan motor. You will probably need to replace it. Before you do that, do check out all the reasons why outdoor AC is not spinning here. Namely, a faulty fan motor is not the only reason why the condenser fan is not spinning.

After you fix this and the fan is spinning again, there won’t be overheating, and the outdoor AC unit will stop tripping the breaker.

How To Call If You Need Professional Help?

As we have seen, both the diagnosis of why the AC keeps tripping the breaker as well as the fixes are not a piece of the case.

From checking the breaker to checking if something is wrong with your AC unit, there is quite a lot of knowledge (and experience) that guys fixing AC units should have.

This article was a general overview of the causes for AC to keep tripping the breaker. If, however, you realize you will a professional help, you can turn to your local HVAC companies.

We hope this helps somebody figure out why the AC keeps tripping the breaker and how to go about fixing it by themselves or with professional help.

Thank you.

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