Why Do Air Conditioners Break On Hot Days
“The A/C quit working, and it’s a hundred degrees outside. It’s almost like the air conditioner knows how much we need it and breaks down on the hottest days of the year.”
This is a statement I’ve heard many times in my 23+ year HVAC career, and it’s funny because it’s true. Although the air conditioner doesn’t have the ability to “know” anything, you’re right your A/C is more likely to break down on the hottest days of the year. This holds true for nearly any electrical appliance.
Heat is one of the worst things for electrical equipment like an A/C. Increased temperatures cause electrical components to run hotter than recommended, and this causes them to fail. When it comes to air conditioning, it is the capacitor and fuses that are most likely to “feel the heat.” There is very little air circulation to cool these components, increasing their chance of failure. I’m not saying that they will blow, just that the odds are better on a hot day.
Here, we will focus on the fuses and how simple it is to fix this problem. Below, you’ll find detailed, step-by-step instructions on how to troubleshoot the problem by:
Let’s get that A/C up and running again without breaking the bank.
How To Remove Fuses
This may all sound like a lot, but honestly, it only takes a few minutes to do. Just pop the fuses back in where you found them and turn everything back on before you sweat to death!
What If I Don’t Have A Voltmeter
For those of you who don’t have a voltmeter, it’s really not a big deal. You should be able to find the size of fuses you need, buy them at your local “big box” retail store, and put them in to test if they were the problem. Worst case scenario is you’ll have an extra set of fuses that you should have anyway and will have only spent a few dollars in the process.
Here, you see the handle is removed and the fuses have been pulled out.
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Clean The Condenser Coils
It’s really easy to clean an air conditioner condenser, and it’s one of the regular maintenance tasks that will extend the life of your unit.
- Aim your garden nozzle upward into the top of the condenser coil to remove the crud buildup under the lid.
- Work all the way around the coil. Then aim the nozzle down and flush the debris down the coil fins.
- Adjust the nozzle to a gentler stream and shoot water directly into the coils to flush out any remaining debris.
What Are Leads And Lugs
- Leads: The voltmeter’s wires. They have hard metal on the end with insulated grips that make the test safe.
- Lugs: The screws on the disconnect that are housed in a metal block. They are the screws that hold the wires down. One should say “line,” and the other should read “load.”
When you test the voltage, you press the metal end of the lead down on the lugs as directed above.
Here the “line” is being tested. The “leads” are what I’m holding here and the “lug” is what I’m touching them to. You can see the voltage reading here.
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Get The Air Conditioning Working Again
I hope this has resolved your air conditioning problem. If it hasn’t, it may be your air conditioner’s capacitor that’s the issue. As I said at the beginning of this article, your air conditioner’s fuses and capacitor are the most likely components to go out on a hot day. So if you tried what I’ve listed here without success, have a look at my article How to Diagnose and Repair Your Air Conditioner Capacitor. It’ll show you how you can find out if it’s a blown capacitor that’s your issue, and what to do about it.
Remember, if what you find in your system doesn’t match up to what I’ve explained here, don’t guess. Contact a professional.
Stay cool, my friends.
This article is accurate and true to the best of the authorâs knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
What Do Fuses Do
Think of a fuse like a secret service agent. It takes the shot. If more amps than the air conditioner can handle try to reach the unit, the fuse will blow to protect the condenser. The fuse is designed to handle a limited amount of amperage based on the maximum amount that the A/C is rated for. If you use a fuse that is too small, the fuse is likely to blow more often, but if you use one that is too big, it could allow more than the rated amount of amperage to reach the unit and cause fatal damage to the system. The same is true of your breakers. Kind of cool, eh?
Why Is the A/C Humming With the Power Off?
The stat tells the furnace to tell the A/C to run. The furnace sends 24v to the A/C contactor, which then connects the power and lets the A/C run, and that makes a humming noise. Obviously, we don’t have any power but the furnace doesn’t know that and will continue to ask the A/C to run.
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Why Does My Air Conditioner Keep Blowing Fuses
If your A/C unit keeps tripping the breaker or blowing fuses, don’t just keep replacing the fuse. When a fuse blows, that’s sometimes your A/C’s way of communicating that there’s a problem. If the fuse keeps blowing then there’s probably a bigger problem with your cooling system and it’s time for you to figure out what it is.
There are many possible causes:
It might be time to hire a skilled HVAC technician or buy a new A/C.
How To Replace A Capacitator
- Take a photo of the wires before disconnecting anything .
- Discharge the stored energy in the old capacitor.
- Use needle-nose pliers to pluck one wire at a time from the old capacitor and snap it onto the corresponding tab of the new capacitor. The female crimp connectors should snap tightly onto the capacitor tabs.
- Wiggle each connector to see if it’s tight. If it’s not, remove the connector and bend the rounded edges of it so it makes a tighter fit on the tab.
- When you’ve swapped all the wires, secure the new capacitor.
WARNING: Discharge the capacitor before disconnecting wires or removing it from its bracket.
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Learn The Anatomy Of A Central Home Air Conditioner
Central home air conditioner service systems consist of two major components: a condenser that sits outside your house and the evaporator coil that sits in the plenum of your furnace or air handler. The refrigerant in the A-coil picks up the heat from your home and moves it to the outdoor condensing unit. The condensing unit fan blows outside air through the condensing coil to remove the heat. The condensing unit houses the three parts replaceable by a DIYer: the AC contactor, the start/run capacitor and the condenser fan motor. The condensing unit also houses the compressor, but only a pro can replace that. The A-coil has no parts that can be serviced by a DIYer.
Replace The Ac Contactor
An AC contactor is a $25 mechanical relay that uses low-voltage power from the thermostat to switch 220-volt high-amperage current to the compressor and condenser fan. AC contactors can wear out and are at the top of the list of common air conditioning service failures. Even if your AC contactor is working, it pays to replace it every five years or so. Unscrew the old AC contactor before removing the wires. Then move the wires to the new unit.
- Yank a connector off the old contactor and move it to the same location on the new part.
- Tighten the connectors where needed.
- Secure the new contactor in the condensing unit.
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This Is How To Replace A Broken Or Melted Disconnect For An Air Conditioning Unit
First thing is go turn off the power at the main electrical panel. Turn off the breaker usually labeled AC and goes to the condenser.
After you think the power is off, grab your volt meter and be sure theres no power.
Now that youre safe and power is off, use a common screwdriver to loosen all the wires.
Undo all the small wire nuts holding together the thermostat wire. Break apart all the thermostat connections but remember how they go together.
Now use a thick common screwdriver and a hammer on the locknut holding the electrical, liquid tight whip onto disconnect. Loosen the locknut by spinning it counter clockwise.
Now remove the electrical connection from disconnect all together.
Unscrew disconnect from the wall.
If, disconnect is glued to the wall. Use a razor knife or screwdriver to carefully break the seal.
Remove disconnect from wall.
Now Take your new disconnect, set it on the ground and with a small tipped screw driver and a pair of crimpers. Break out the 2 knockouts to match the old disconnects holes.
Now screw disconnect to the same spot the old one was mounted and reconnect the electrical whips exactly as before. Dont forget to put your locknuts back on the whips.
Now put the 2 ground wires, 1 from each whip into the ground nut and tighten them down.
Push the ground wires back and out of the way.
Put both the wires from the home to the line side of disconnect. L1 and L2
Put together all the thermostat connections as you found them but cleaner.
Common Ac Disconnect Problems
An AC disconnect is also known as an air conditioner switch box or fuse box. It contains the controls for the main energy supplier of the air conditioner, like the breakers and fuses. It also protects the wires of the air conditioner from weather and other outdoor elements. Usually AC disconnects are found outside, with the end of the AC showing inside the house. This is because the AC needs to expel hot air. An AC disconnect box can either be a pull-out or an enclosed molded case. The latter is preferred because it withstands the elements of weather better. Most houses have air-conditioners nowadays because air conditioners have dual functions, they can cool the air and they can also clean the air.
In todays modern technological era, air conditioners play a vital role, thus AC disconnect leads to a lot of inconvenience and hassle. Many people rely on AC to be able to live a comfortable life. Keeping your ACs switch box in proper working order not only guarantees the safety of your family, but it also helps your air conditioner last longer. Make sure to always check on the air conditioner box and make the necessary repairs as soon as you think one is needed. When it comes to anything technical or anything that involves electricity, it is best to ask trained professionals to do it for you, or at least ask them for a consultation. Major disasters and unnecessary accidents will be avoided if you seek professional advice.
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Inspect The Inside Of The Access Panel
Follow the electrical conduit from the house that’s where you’ll find the access panel. With the power off, remove and store the access-panel retaining screws and remove the panel. Before you replace any parts, check for rodents’ nests or evidence of chewing on wires and electrical connectors.
If you find broken wires or chewed insulation and can safely handle electrical repairs, discharge the capacitor first. Then repair the wires and clean out the nest. Otherwise, call a pro.
How To Check If Your A/c Fuses Are Blown
If you suspect your fuses may be blown, the first thing you’ll notice is that the A/C unit outside is not doing anything. You may hear a slight humming, but that’s all. The best way to check the fuse is by using a voltmeter. Let’s go through this process first.
For those of you who don’t have a voltmeter or are uncomfortable testing voltage, I will give you another method for checking the fuses.
Warning! You are working with live electricity here. We cannot test fuses and voltage with the power off or the fuses removed. You should not attempt to work with live electricity if you are not a skilled electrician. In this case, we are taking a simple voltage reading but must still be careful and confident in what we are doing.
Note: Not all disconnects have fuses in them. Though it is most common that they do, and it’s code in many states, some do not. If that is the case, they would not be your problem.
An air conditioner disconnect.
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Replace The Start/run Capacitor
All air conditioning service units have at least one capacitor. The capacitor stores electricity and releases it during compressor and condenser fan startup to give both motors an extra jolt of power. And it smooths out voltage fluctuations to protect the compressor and condenser fan motor from damage.
Capacitors can degrade slowly, providing less startup power over time. Or they can fail in an instant. Gradual capacitor failure can go unnoticed for a long time, stressing the compressor and condenser fan motor windings, resulting in their early failure. Since capacitors are cheap, it pays to proactively replace yours about every five years.
How To Test The Voltage On An Air Conditioner
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