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Home air conditioner troubleshooting

When there’s something wrong with your central air conditioner, it usually means calling in a technician to fix it. This can be expensive and even put you in the waiting game while you roast during a heat wave. Fortunately, there is some basic air conditioner troubleshooting you can perform first.

Knowing some key things to check about your system can often lead to a solution you can do yourself. If the problem is beyond your scope to fix, at least your own upftront troubleshooting can inform you better about what’s wrong.

This article will help teach you how to troubleshoot your air conditioner and provide you with some understanding on available solutions. This is helpful when dealing with a service professional and get you “in the know” as you work with them. After all, it’s your hard-earned money at stake – in other words, don’t just take someone’s word for what they’ll charge you for; seek to understand the problem and what they’re doing to repair it.

Air conditioner troubleshooting guide

Below are the top four symptoms we face when things go awry with our home cooling appliances. Depending on what you’re experiencing, each gives you a description of what could be going on and how to check into it as you go about troubleshooting the entire air conditioning system. Where it makes sense, suggestions are given to help inform you when it’s time to call for service.

Air conditioner won’t turn on

If your air conditioner won’t turn on, it’s most likely a problem with the thermostat itself or an electrical issue causing a component of the system not to receive power. Let’s look at how to troubleshoot.

How to fix
If you suspect a thermostat problem, verify you’re reading it correctly. As you know the air temperature must be above the thermostat setting in order for the system to be told to run. Adjust the dial, lever, or up/down buttons accordingly. Some thermostats have a wait-time of 5 minutes or more if the compressor has been on recently. This is to prevent damage to the compressor from restarting too soon.

To check power problems, you’ll need to confirm power in three places. First, confirm your thermostat is receiving power. This is usually low voltage. Digital models will obviously show a reading on their displays. Analog types (ones with dials or levers) may have to be checked with a meter after lifting off the front cover.

Your compressor outside your house must be getting power of course. If it isn’t kicking on and its cooling fan isn’t spinning, check for switches outside and at the breaker box. See if the A/C fuse is still in good shape and not tripped.

Your central air system’s main blower is located indoors, either in a garage, basement or closet. Ensure it is plugged in, the outlet it uses is functioning properly (if applicable) and that the circuit it’s on has not been tripped at the breaker box.

Air conditioner not cooling

Nothing is worse than turning on your air conditioner, and only “warmish” air comes out. There are a few basic issues at play that usually involve some quick maintenance tasks as part of your air conditioner troubleshooting project.

The most common cause is refrigerant. This is the magic stuff that condenses, cool and circulates to an evaporator coil where it’s warmed as air passes over it to cool your home. Other issues can be related to airflow restraints.

How to fix
Troubleshoot air conditioner refrigerant issues by checking the condenser unit outside and the line that carries it to the evaporator coil inside. Have there been any leaks? If so, that’s your problem. Over time, refrigerant needs to be recharged or replaced altogether. This is a time when a technician will need to come out and check the fluid levels and quality of your refrigerant.

As for airflow, always check for stoppages at the filter or kinks in lines coming from the outside. Ensure the blower is on full throttle and doesn’t need belts.

System cycles on and off too much

This issue can not only become annoying, it is not very energy efficient as the compressor draws a heavy load of electricity each time it starts up.

The two most likely causes of quick cycling is either a faulty thermostat or problems with airflow. Airflow blockages somewhere in the system are usually to blame.

How to fix
It’s a good idea to check your thermostat first since this is the easiest to  look at. Ensure that internal contacts are clean of dust and grime build-up. If you have an old (non-digital) model, ensure it is level. Follow other thermostat troubleshooting points here.

Air not moving freely (as it should) through the system can cause air conditioners to turn off and on too frequently. Troubleshooting the air conditioner’s airflow involves the following:

First check that the cooling fan is working properly outside at the condensing unit. It’s important to keep the compressor from heating up too much. Check the main blower (at the furnace) and make sure it is free of dirt build-up and debris, and is running properly. Finally, verify that the filter is clean and of the correct type. If you have many registers/vents in your home, make sure they are all open and that doors to rooms are not shut. You want air to flow as freely as possible as to not strain the system as you troubleshoot.

Cool in some rooms, warm in others

Remember, your goal is to cool your house evenly for the most efficient use of any air conditioner you’re troubleshooting. Unfortunately this doesn’t work in some homes, despite your efforts. Inconsistent airflow throughout the house can make for uneven cooling from room to room. There are some ways to diagnose the problem and fix it however.

The two biggest causes of this issue have to do with your duct work being out of balance and the size of your actual air conditioning unit. One requires a little investigating, while the other may involve some significantly extra costs.

How to fix
To troubleshoot an air conditioner duct system is fairly easy. You can physically feel the amount of air coming out of a given register. You can also feel or use a thermometer to tell you that some rooms or parts of the house just aren’t getting cool enough.

To remedy, you need to get acquainted with the route air takes from your central blower. Your goal is to then send more air to warmer rooms and less to cooler rooms. You can do this by shutting register covers in cooler rooms. The more efficient method though is to add or adjust dampers along the duct work line or add a duct work booster fan.

Dampers open and close to let more or less air pass through. These are designed to help you balance your system, and are usually installed in accessible areas, such as in basements or attics easily accessed. You can add dampers if necessary as they really do help to route air according to the needs of your home.

If you’ve balanced your duct system and still have problems, your A/C may not be big enough for your home size. In other words, it may not be able to keep up (create enough condensed cold air for the blower to distribute around your house). Check the BTU capacity and compare to the volume of your living space.

Again, most air conditioner troubleshooting can be performed by you, the homeowner. It just takes a little knowledge to know where to look. As you make adjustments, you are in fact tuning your own A/C. But even so, there are times when a professional tune-up can get you back to running in full performance mode.

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