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You are in Phoenix. We also have a Tucson site.

You are in Phoenix. We also have a Tucson site.

Quick Fixes For When Your AC Unit Won't Turn Off


Imagine this: it's the hottest day of summer, and your AC is running non-stop. Panic sets in as you watch your energy bill skyrocket. Don't worry! This article dives into common reasons why your AC won't turn off and offers practical troubleshooting steps. We’ll also guide you on when it’s time to call a professional, so you can quickly get your system back to working condition.

Key Takeaways

  • If your AC won’t turn off, it could be due to thermostat malfunctions, electrical component issues, dirty or clogged components, or an incorrectly sized system, which can increase energy bills and reduce system efficiency.

  • Basic troubleshooting steps for an AC that won’t stop include adjusting thermostat settings, cleaning or replacing air filters, inspecting and cleaning the outdoor unit, and checking for frozen evaporator coils, which can sometimes be fixed without professional help.

  • Seek the expertise of a professional if electrical problems persist, if the air conditioner still doesn't cool after thorough troubleshooting, or if it's time for a system replacement or upgrade.

Common Reasons Your Air Conditioning System Won't Turn Off

An AC running continuously is like a marathoner begging for a break and some much-needed TLC. The root of this problem can typically be traced back to one or more of the following:

  • Dysfunctions in the thermostat

  • Problems with electrical components

  • Dirtiness or blockage in system parts

  • An improperly sized unit

These issues disrupt your air conditioner’s usual performance, causing it to run non-stop and struggle to circulate cool air effectively. If your air conditioner won’t turn off, it’s time to roll up your sleeves and dive into some troubleshooting.

These problems are more than just annoying—they're also a drain on your wallet, with your AC system working overtime and driving up your energy bills. Let’s break down each of these potential causes to better understand how they impact your air conditioner's performance and what you can do about them.

Thermostat Malfunctions

A malfunctioning thermostat frequently leads to problems with the AC unit. If the air conditioner won't turn off due to thermostat malfunctions, such as impaired sensors or loose wiring connections, the thermostat may fail to communicate correctly with the AC unit, leading it to overwork and cool excessively. This can result in unnecessary energy consumption. A properly functioning thermostat is crucial for maintaining normal cooling cycles, typically lasting 20 to 30 minutes with the AC unit completing two to three cycles each hour. Monitoring the duration and frequency of the cooling cycle is essential; if the cooling unit is constantly running for hours, it indicates a problem that leads to electricity wastage, increased wear and tear, and potential system malfunctions that need immediate attention.

To ensure your thermostat is working correctly, regularly check for loose wiring connections and clean any dirt or debris from the sensors. If you notice any irregularities, consider replacing the thermostat or consulting a professional for further inspection.

Electrical Component Issues

Electrical component issues often result in an air conditioner that won't stop running. Problems such as a stuck relay switch or a defective compressor contactor can cause the AC unit to operate continuously, even when it’s not necessary.

If the compressor contactor is welded shut, it will lead to a continuous power supply to your AC system. This not only risks damaging your unit but also increases energy consumption. Promptly addressing electrical issues is crucial to prevent damage and ensure efficient operation of your air conditioning.

If your AC system experiences a short circuit that prevents it from turning off, you need immediate attention from an expert. Complex problems such as faulty wiring or defective parts that cause the unit to run non-stop require the expertise of a certified HVAC technician. For air conditioners that have been in operation for over a decade, recurring electrical difficulties are common. An expert evaluation is necessary to decide on the right course of action.

Electrical issues are often serious and should be handled with great care. We strongly advise contacting a professional to address them safely and effectively.

Dirty or Clogged Air Filter and Components

A contaminated air filter or debris-covered condenser coils in your AC unit can cause it to run incessantly. When an air conditioner’s air filter becomes dirty, the flow of air is impeded, prompting the system to engage in continuous cooling cycles just to maintain a proper level of coolness.

When grime accumulates on the evaporator coils, it can cause longer cooling periods because the coils cannot absorb heat effectively. This situation could also lead to instances where instead of circulating cooled air, the blower fan dispenses warm air. During its operation cycle, if foreign materials like leaves and grass trimmings obstruct the outdoor condenser unit, airflow gets restricted, forcing your AC into overdrive as it strives to maintain a cool temperature.

Regular maintenance, such as clearing debris from the condenser, can prevent this issue. If adding routine maintenance to your plate sounds impossible, consider investing in a maintenance plan, which ensures your system is regularly checked and maintained.

Incorrect System Size

If your air conditioner is too small for your home, it's like a little engine that could... but can't. It keeps chugging along, trying to cool down your space, but it never quite gets there. This means it's always on, working overtime and driving up your energy bill without ever giving you the comfortable home temperature you're looking for.

On the flip side, if your AC is too large, it cools your house faster, but it also shuts off too soon. This short-cycling can wear out your system and leave some rooms feeling like a sauna while others are more like a freezer.

The Goldilocks solution? A just-right AC size that efficiently meets your cooling needs without overworking. If you're stuck in an endless cycle of too hot or too cold, it might be time for an upgrade to an air conditioner that's sized perfectly for your home.

Simple Troubleshooting Steps for a Non-Stop AC

Delving into basic troubleshooting techniques for a continuously operating AC, here are some simple actions you can perform:

These troubleshooting tips can guide you through pinpointing and tackling the issue, potentially helping to avoid having to call in a professional. However, if these DIY fixes don’t cut it, it’s best to bring in a HVAC professional to avoid further damage to your AC system.

Adjust Thermostat Settings

When addressing an air conditioner that won’t stop running, a good initial action is to modify the thermostat’s temperature settings. Set temperature slightly above what is currently in the room. This will enable the cooling system to shut off after reaching your preferred level of coolness.

Make certain that your thermostat fan setting is switched to ‘Auto.’ This ensures that both the cooling system and fan halt once they have reached the pre-determined temperature, all thanks to a component known as the fan limit switch. Incorrect settings on your thermostat could cause continual operation of your air conditioner, leading it not only to overly cool but also waste energy.

Should you suspect malfunction within your thermostat itself, try changing out its batteries whether in a wall-mounted control unit or hand-held remote. Doing so might just re-establish correct functionality and control over maintaining desired indoor temperatures.

Clean or Replace Air Filters

For optimal air conditioning performance and to prevent it from cycling on and off excessively, it’s vital to regularly replace the air filters. Check your AC’s air filters every 15 days and aim to replace them once a month during periods of heavy use.

If you reside on the ground floor, have indoor pets, smokers, or someone in your home suffers from allergies, you may need to clean or replace your air filters more frequently. Regular attention to clogged air filters will maintain superior airflow quality and enhance overall system efficiency.

Inspect and Clean Outdoor Unit

Examining and cleaning the outdoor unit is a critical step in addressing issues with persistent operation. To clean the AC condenser, first, ensure the power is turned off. Then, unscrew and remove the access panels.

To enhance airflow and efficiency of your air conditioner, follow these steps:

  1. Remove any debris surrounding the condenser.

  2. Utilize a hose or specialized cleaners for scrubbing down the condenser coils.

  3. Use vertical strokes with a brush to clean the fins on your condenser. Alternatively, guide water from above downward using a hose to rinse them off.

Once you’ve finished cleansing, reinstall all panels back into place by reversing their removal process. Start attaching screws loosely before fully tightening them to secure everything in place.

Check for Frozen Evaporator Coils

Inspect the evaporator coils to determine if they have frozen over. When these coils freeze, it hampers the air conditioner’s ability to effectively extract heat due to reasons such as:

  • Accumulation of excessive dirt.

  • Insufficient flow of air.

  • Levels of refrigerant that are too low.

  • Components in the condensate drain that are blocked.

Follow these guidelines to address an issue with frozen coils:

  1. Power down the AC unit so that thawing can begin.

  2. Examine and remove any obstructions from the air filters.

  3. Accelerate the defrosting process using a fan or employ a hair dryer at a low setting carefully to avoid damaging the coils through cracking.

  4. Wait until the evaporator coils are completely dry after the ice has melted.

  5. Gently clean the unit.

  6. Finally, verify that there’s nothing obstructing airflow around your outdoor unit before turning the AC unit back on—keeping this area free from debris helps prevent ice buildup.

When to Call a Professional

There might be instances where, despite your initial troubleshooting efforts, professional assistance becomes necessary. Continuous operation of your air conditioner, persistent electrical issues, or the need for system replacement or upgrades are clear indicators that it's time to call in a professional.

Parker & Sons: Your AC Solution in Arizona

At Parker & Sons, we bring nearly fifty years of experience in providing top-notch air conditioning services to both homeowners and businesses. If your air conditioner won't stop running despite your troubleshooting efforts, our expert team is here to offer reliable solutions. Don't let a malfunctioning AC disrupt your comfort—call us today to schedule immediate HVAC maintenance!

Frequently Asked Questions

Why is my AC still on after I turn it off?

Your AC seems may be suffering from multiple problems, including a clogged air filter, frozen evaporator coils, or even a faulty thermostat.

How often should I replace my air conditioner's filters?

To guarantee peak performance from your air conditioner, we recommend changing the air filter once a month during periods of heavy use.

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