Why does a home central air conditioner trip the breaker

This post will give you various reasons as to why does a home central air conditioner trip the breaker.

There are various types of systems and breakers so I will categorize this post to address each one.

The breaker for the outside condenser is typically a 30, 40, or 50 AMP 2 pole breaker. I’m going to make a list of the reasons that breaker trips and then I will break down each of those reasons with the repair solution for each. If your breaker is for a different component then please read below for the other components to your HVAC system and why that breaker will trip.

The main tool required to troubleshoot is a multimeter. A cheap one will do just fine. Take your time and be patient this is not hard to figure out. If you read this carefully with no distractions you can figure this out saving you time and money.

  • Disclaimer – Read the disclaimer at the bottom of the page.

Reasons the Condenser (compressor) breaker is tripping.

  • Capacitor is very weak or bad.
  • One of the wires going to the compressor, contactor, or capacitor is shorting out.
  • Disconnect box has burned connections or wires shorting out.
  • This is [RARE] however, the wires inside the A/C whip short out.
  • Possibly the compressor motor is bad internally and shorting out to ground.
  • Very RARE however, I do run into this every once in a while the contactor will short out.
  • The plug on the side of the compressor may be melted and shorting out.
  • Normally the breaker just doing it’s job. But ocassionally it trips because its just bad.
  • The breaker may be lower amperage than required. However, it can’t go higher than the conductor rating.

Reasons the Air Handler (Inside unit) is tripping the breaker.

  • Blower motor is bad or overheating and going bad.
  • Capacitor on the blower motor is weak or totally out.
  • The internal heat strips are bad and shorting out on the metal shell of the unit.
  • Some air handlers have an inside power disconnect in the attic or closet that has went bad.
  • Main feeder wire feeding power to the air handler is shorting out.

Reasons the Furnace is tripping the single pole 15 or 20 AMP breaker.

  • The blower motor is bad or overheating and going bad.
  • Circuit control board is bad and has a direct short.
  • Transformer is bad. Some systems have more than one transformer.
  • A wire is shorting out on the metal shell of the unit.
  • Some furnace systems have a capacitor for the blower motor that go bad and trip the breaker.
  • The inducer fan motor is bad and shorting out.

Breakdown of the condenser breaker tripping and how to solve it.

Capacitor Bad – If the capacitor is extremely weak or totally bad then it may have a swollen top and or bottom. If you see the capacitor is swollen then it needs to be replaced. If the capacitor has no visual expansion or leaking fluid then you will need to test it with a voltmeter. The capacitor will have a sticker on it that says what the capacitor rating should be in microfarads. If you test the capacitor and it reads 10% or less than the number on the capacitor then it may cause the breaker to trip. The reason the breaker trips is because the condenser fan motor or compressor motor is pulling more amps because the capacitor isn’t strong enough to assist.

Why does a home central air conditioner trip the breaker
A swollen capacitor top which, will trip a breaker

Wire Shorting out – The wires in the service compartment with the capacitor and the wires going to the compressor motor will sometimes short out on something metal. If the wire is aginst something metal this will make the breaker trip. The wires will need to be visually inspected.

Bad disconnect box – The disconnect box is a small grey box on the side of the home that has an electrical A/C whip going to the condenser. The inside of that box will need to be inspected. Some disconnect boxes have a fuse and some of them don’t. The compartment will have the line wires coming in from the panel and that same compartment will have the wires that go to the condenser. Look at all of the wires and inspect the whole inside of the disconnect box for burn marks or metal that looks discolored or overheated. If nothing looks wrong then it’s most likely not the disconnect box causing the breaker to trip. However, if you see burn marks or any bad metal discoloration then you need to have that changed. It may be tripping the air conditioner breaker.

picture of a Disconnect box and whip

Bad Wires Inside A/C Whip – I don’t run into this very often but, I do about 1 time every year. Running thousands of service calls and only happening 1 or 2 times per year isn’t very much. I wanted to put it here because it does happen. This is easy to check by toning out with a multimeter. If you don’t have a multimeter you could inspect each wire by pulling them out of the AC whip. However, I would invest in a cheap multimeter before I would do that.

Bad Compressor motor – If the compressor motor is shorting out internally then the 2-pole breaker will trip as soon as you try to click it on. You can test the compressor by testing the wire leads.

reasons why the air conditioner breaker will trip
reasons why the air conditioner breaker will trip

The contactor is bad – It’s rare that I run into a breaker tripping on a condenser because of a contactor. However, I do occasionally find that they do trip the breaker. If the contactor is so bad it’s tripping the breaker you may be able to see the damage. If not you will need a multimeter to test the low and high voltage.

Reasons a compressor wont start
Reasons a compressor won’t start

Compressor plug bad – If you look inside the compressor you will see the wires going down to the plug that connects to the side of the compressor. Sometimes all it takes is looking at the compressor plug. You may see that it is melted or badly deteriorated. If this is the case this would definitely trip the air conditioner compressor. The compressor plug would need to be popped off and inspected.

Picture of a compressor with the plug on the side

Bad Breaker – Sometimes the breaker is just bad. This is not normally the case. Most of the time when the breaker is tripping, the breaker is just doing its job. The job of the breaker is to shut off or trip when it senses an unsafe condition. If you switch the breaker from the off to on position and feel it is weakly clicking in place or just doesn’t feel right then you should have the breaker replaced.

Breaker under rated – If the breaker was originally put in at the minimum allowable amperage that the condenser allows it may trip. The reason it starts tripping in this situation is that the condenser is aging and the amperage is increasing as the age of the motors increases. You can’t just increase the amperage of the breaker unless the wire conductor is the correct size to accept the larger breaker size. If the wire size is larger than the breaker rating that was on then the larger breaker can be installed.

Breakdown of the Airhandler breaker tripping and how to solve it.

The air handler is on the inside of the home in almost every case with the exception of a few areas of the country.

Blower motor – The blower motor in the air handler is bad or overheating and going bad. Sometimes the motor is overheating and it’s because the capacitor is weak or bad. The motor may not be bad. If the capactor is bad the motor may just overheat to the point the internal temperature switch stops the motor. But the breaker may also trip because the electrical wire overheats.

reasons why the air conditioner breaker will trip
reasons why the air conditioner breaker will trip

Capacitor on blower motor – The capacitor on the blower motor may be bad. This will occasionally cause the breaker to trip. Test it with a voltage meter. If it is weak it should be replaced.

Heat strips (coils) – An air handler has electric coils on the inside. If the electric coils break from age or other reasons it is possible for it to short out on the metal cabinet. If this happens it will trip the breaker. In this situation, the heat strips will have to be replaced.

Bad air handler disconnect – Similar to the condenser. The inside air handler may have a grey disconnect box. That box needs to be inspected. Look for burn marks to determine if the internal wires are shorted out.

Main electrical wire – This does not happen very often but, if all other inspections haven’t turned up any problems then you can trace out the main wire or wires. If you find a part of the wire that has shorted out because of physical damage then you need to have a licensed electrician repair the wire with a junction box.

Breakdown of the Furnace breaker tripping and how to solve it.

Blower motor – The blower motor may be going bad or is totally bad and is causing the breaker to trip.

The capacitor on blower motor – The capacitor on the blower motor may be bad. This will occasionally cause the breaker to trip. Test it with a voltage meter. If it is weak it should be replaced.

Circuit board is bad – If the circuit board is bad it can trip the 15 or 20 amp single pole breaker on the furnace. Some of the time the board will have burn marks and it’s fairly easy to see it’s bad. If you can’t see any burn marks then you will need to have a multimeter to troubleshoot the board.

why does my ac keep blowing the 3 amp fuse
Burned circuit board mark

Bad Transformer – Some systems have more than 1 transformer on the furnace. In order for the transformer to trip the breaker, it would most likely have physical damage. It may have melted. If it melted you will smell an electrical burning smell.

reasons why the air conditioner breaker will trip
reasons why the air conditioner breaker will trip

Wire shorted out – Visually inspect the wires on the inside to ensure the wires are not shorting out on the metal shell.

Bad Inducer Fan Motor – The inducer fan motor comes on before and during the furnace burner ignition. I don’t have them trip the breaker very often. they normally just go bad and the furnace won’t work. However, they will every once in a while cause the breaker to trip.

reasons why the air conditioner breaker will trip
reasons why the air conditioner breaker will trip

If you are patient and have a multimeter you can work your way through the system fast and troubleshoot the issue. Maybe it can be fixed at that moment or maybe it needs to fixed at a later time.

The good thing is you will know exactly what part is bad and not overspend or waste your time.

If this post helped you in some way please leave a comment below.

* WARNING! This post and information on this website are for trained and certified technicians only. It is for educational purposes only. Under no circumstances should anyone who is not qualified or have the required permits or licensing attempt to use any information in this post to try and repair an HVAC or electrical system on their own. The opinions and methods I use are my opinions and I give no guarantee of any type of outcome. In other words, if you are not a trained and certified technician you should not attempt any repairs on your own. You should hire a licensed professional to do the work.  

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