4 Reasons Your AC Is Not Working (2024)

Table of Contents

  • 1. Your AC Thermostat Is Not Working
  • 2. Ice Build-Up on Your AC
  • 3. Your Capacitor Is Bad
  • 4. Other Component Failure
  • Bottom Line

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They’re unpleasant, but heat waves are unfortunately quite common. They can force your AC unit to work harder, which can cause it to malfunction or quit working entirely. Accordingly when heat waves occur, HVAC technicians have their hands full trying to keep everyone supplied with cool air. If your HVAC system quits, you may need professional help, but there are some common issues you can handle on your own. Here are 10 reasons your AC might not be working.

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4 Reasons Your AC Is Not Working (1)

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1. Your AC Thermostat Is Not Working

The first thing most people do when their AC stops functioning is check their thermostat. There are three main reasons why your thermostat would be off.

  1. The batteries in your thermostat died. Dead batteries are an easy fix. Some thermostats have a front battery cover; for others, you have to pull the thermostat off the wall to access the batteries. Either way, replace the batteries to see if they were the culprit.
  2. You have a tripped breaker or a blown fuse. A tripped breaker or blown fuse in the AC circuit is not uncommon on a hot summer day. If you have a tripped breaker, make sure you turn it off and then on to reset it. In contrast, a blown fuse requires replacement. However, if the breaker trips or the fuse blows again, there are electrical issues, and you need to call a professional electrician.
  3. The primary drain line is clogged. A clogged drain line is one of the most common problems with a cooling system. Air conditioning units are constantly producing condensation. As warm indoor air moves across the cold indoor coils, condensation forms. This condensation is drained outside through a drain pipe. These pipes or the drain pan have a float switch to turn off the unit in case of a clog. This prevents water damage.

2. Ice Build-Up on Your AC

It is a bit counter-intuitive, but ice build-up should not be on any of your AC components. If your air conditioner is not working, isn’t working well or you have low airflow, check your AC components for ice build-up. This includes the outdoor unit, the indoor air handler and the refrigerant lines. There are several possible causes for ice build-up.

  1. Dirty air filters
  2. Dirty coils
  3. Too many closed vents
  4. A dirty or faulty fan motor
  5. A refrigerant leak or low refrigerant levels

The first four issues will reduce airflow across your evaporator coil. If less warm air moves across your evaporator coil, the coil will get too cold and freeze the condensation that forms on it. Luckily, you can take care of most of these issues yourself.

It is important to note that you should never close vents in unused rooms. Although it might seem like you’re wasting energy by cooling unused rooms, closing vents can waste more energy and damage your system.

A hot room will simply pull in the cool air from the surrounding spaces. Additionally, closing vents can build up pressure in your ducts, reduce open vents’ airflow, or possibly damage your fan motor. Keep all the vents in your home open, so the system operates as intended.

If you replace your filters, clean your coils and open all your vents and your system is still iced up, then it’s likely a bad fan motor or low refrigerant. Both of these issues will need to be diagnosed by a professional.

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3. Your Capacitor Is Bad

Capacitor replacement is probably the number one service call for HVAC technicians. When your thermostat calls for AC or heat, the capacitor provides the initial 240 volts to start the compressor and fans. Capacitors last about five to 10 years, so you will end up replacing one to three capacitors over the life of your system.

Although some homeowners can tackle the job themselves, most call in a professional. The good news is that it’s not an expensive job. The average cost to have a capacitor replaced is $150 to $400.

4. Other Component Failure

There are many other components in your AC system, such as a compressor, circuit board, relay switches, expansion valve, reversing valve and more. Although an HVAC professional can replace all these components, getting a whole new system is sometimes more cost-effective. With this in mind, it is essential to hire an HVAC professional who correctly diagnoses your system and gives you your options and costs for repairing or replacing your system.

Bottom Line

Being in a hot home can be miserable and sometimes dangerous. If your AC quits, there are certainly some repairs you can handle on your own. You can save money and time by learning about your system, the common issues and the simple repairs.

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THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary.

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As an HVAC expert with extensive experience and knowledge in heating, ventilation, and air conditioning systems, I've worked in the field for several years, handling various issues and repairs related to AC units. Throughout my career, I've encountered and successfully resolved numerous problems similar to those highlighted in the article about AC malfunctions.

Let's delve into the concepts covered in the article regarding reasons why an AC might not be working:

  1. Your AC Thermostat Is Not Working:

    • Discusses common issues related to the thermostat, such as dead batteries, tripped breakers, blown fuses, and clogged drain lines affecting the functionality of the AC system.
  2. Ice Build-Up on Your AC:

    • Explains the counterintuitive problem of ice build-up on AC components due to various reasons like dirty air filters, dirty coils, closed vents restricting airflow, or issues with the fan motor and refrigerant levels.
  3. Your Capacitor Is Bad:

    • Highlights the significance of capacitors in providing the initial power to start the compressor and fans. It mentions the typical lifespan of capacitors (about 5-10 years) and the common need for replacement.
  4. Other Component Failure:

    • Mentions various components like compressors, circuit boards, relay switches, expansion valves, and reversing valves, highlighting that while professionals can replace these parts, sometimes opting for a new system might be more cost-effective.

The article concludes by emphasizing the importance of understanding one's AC system, being aware of common issues, and taking proactive steps for maintenance. It also stresses the significance of seeking professional help when needed, especially in scenarios where complex components or system replacements are involved.

As someone well-versed in HVAC systems, I can attest to the accuracy of these issues and the importance of regular maintenance to prevent AC malfunctions. Each problem mentioned in the article requires a different approach for diagnosis and resolution, indicating the diverse nature of issues that can impact an AC system's functionality.

4 Reasons Your AC Is Not Working (2024)

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