Troubleshooting Your AC: What to Do When It Keeps Turning On and Off—Advice from The Lee Thompson Co.
When your AC starts cycling on and off frequently, it can be both frustrating and a sign that something isn’t quite right. Before you reach out to the professionals, there are a few troubleshooting steps you can take to try and resolve the issue on your own.
At The Lee Thompson Co., we’ve been Houston’s trusted HVAC experts since 1961, and we’re here to help you keep your home comfortable.
In this blog, we’ll guide you through some simple steps to identify and potentially fix the problem, so you can decide if it’s something you can handle or if it’s time to call in our team.
Why Your AC Keeps Shutting Off and On
To troubleshoot why your AC keeps turning on and off, it’s crucial to grasp the basics of how it operates and the concept of short cycling. Your AC unit is a complex system designed to remove heat and humidity from your home. Here’s a simple explanation of how it works:
- Refrigerant cycle: A special fluid called refrigerant circulates through a closed-loop system in your AC unit. It absorbs heat from indoor air, transforming from a liquid to a gas. The gas then flows to the outdoor unit (condenser), releasing the heat and returning to a liquid state, ready to start the cycle again.
- Thermostat’s role: Your thermostat acts as the control center, monitoring the indoor temperature and signaling the AC to turn on or off to maintain your desired temperature.
What is short cycling?
Short cycling refers to the AC unit turning on and off frequently, often running for only a few minutes at a time. Instead of completing an entire cooling cycle, it prematurely shuts off and restarts, leading to a cycle of short bursts of operation.
Short cycling forces your AC to work harder than necessary, resulting in higher energy bills. The constant starting and stopping also strains the AC’s components, leading to premature wear and tear and potentially costly repairs.
Additionally, short cycling prevents your AC from running long enough to properly dehumidify the air, making your home feel less comfortable. The added stress can cause damage to the compressor, the heart of your AC system, which can be a major expense to replace. Understanding the root causes of short cycling is key to fixing the issue.
Here’s a breakdown of the most common culprits of short cycling:
- Thermostat issues – A faulty thermostat might send incorrect signals to your AC, causing it to shut off prematurely. If your thermostat is placed in direct sunlight or near a heat source, it might be sensing a higher temperature than the actual room temperature, leading to short cycling.
- Refrigerant issues – Insufficient refrigerant can cause your AC to overheat and shut down. A qualified technician should address refrigerant leaks. If your AC is low on refrigerant, it’s often due to a leak in the system, which requires professional repair.
- Airflow problems – Clogged filters restrict airflow, causing your AC to work harder and potentially overheat. Reduced airflow can also cause the coils to freeze, leading to short cycling.
- Electrical problems – Damaged or loose wires can disrupt the electrical signals that control your AC. The capacitor also helps start the compressor. If it’s failing, your AC might have trouble starting or running.
- Oversized AC unit – If your AC unit is too large for your space, it will cool the area quickly and shut off before a full cycle is complete, leading to short cycling. This is less common but worth considering if your AC has always cycled rapidly.
- High ambient temperature: On extremely hot days, your AC might struggle to keep up with the demand, leading to frequent on/off cycling.
- Dirty condenser coils: The outdoor unit’s coils can accumulate dirt and debris, hindering heat dissipation.
By understanding these common causes, you can begin to troubleshoot your AC issue and take the necessary steps to restore its normal operation. If you have any questions or need further assistance, the experts at The Lee Thompson Co. are always ready to help. Contact us at (713)766-4846 for more information and support.
AC Short Cycling: How To Fix
Before you start troubleshooting, remember safety first! Always turn off the power to your AC unit at the circuit breaker before performing any maintenance or repairs. This will prevent electrical shock and protect both you and your equipment.
#1 Check and replace air filters.
Dirty filters restrict airflow, forcing your AC to work harder and potentially overheating, leading to short cycling. To check, locate your air filter(s)—usually behind a return air grille or within the air handler unit—and inspect for dirt and debris buildup. You must replace filters every 1-3 months, or more often if you have pets or live in a dusty environment. Refer to your AC unit’s manual for the recommended filter type and size.
To replace air filters, turn off the power, remove the old filter, and insert the new one, ensuring proper airflow direction (indicated by arrows on the filter frame).
#2 Clean condenser coils.
The condenser coils, located in the outdoor unit, dissipate heat. When dirty, the AC becomes less efficient and may overheat, leading to short cycling. To clean condenser coils:
- Turn off the power to the outdoor unit.
- Carefully remove the protective grille or cover.
- Rinse with a hose (low pressure) from the inside out and allow to dry completely.
#3 Check and Clean Vents.
Blocked vents or registers restrict airflow, making your AC work harder and potentially causing it to overheat. Be sure to inspect all supply and return vents for obstructions. To clean, remove any furniture, rugs, or other items blocking the vents. Use a vacuum or duster to remove dust and debris from the vents and grilles.
#4 Reset circuit breaker.
Sometimes, a tripped circuit breaker can cause your AC to shut down unexpectedly. To reset, locate your electrical panel and identify the breaker that controls your AC unit. If the breaker is tripped (in the “off” or middle position), switch it fully off and then back on.
#5 Inspect the thermostat.
A malfunctioning or incorrectly set thermostat can send erroneous signals to your AC, causing short cycling. To inspect, check the thermostat settings to ensure they are in cooling mode and set to your desired temperature. Replace batteries if needed. Some thermostats have calibration options. Refer to your owner’s manual for instructions.
#6 Restart your AC.
Sometimes, a simple restart can resolve temporary glitches. Turn off the AC at the thermostat and breaker, wait a few minutes, then turn them back on.
#7 Check for ice buildup.
If you see ice on the evaporator coils (indoor unit) or refrigerant lines, it indicates a problem that requires professional attention. Turn off the AC and let the ice melt completely before calling a technician.
When to Call a Professional
While many AC short cycling issues can be resolved with DIY fixes, some problems require professional expertise. Call a qualified HVAC technician if:
- You suspect a refrigerant leak.
- The electrical components (wiring, capacitor) appear damaged or faulty.
- You’ve tried the above DIY fixes, but the problem persists.
For easy, affordable maintenance, sign up for The Lee Thompson Co.’s Home Comfort Maintenance Plan, and rest easy that your unit is taken care of. Our maintenance plan includes bi-annual maintenance and a load of other benefits. Call us anytime at (713)766-4846 or visit https://leethompsonac.com/home-comfort-plans/ to learn more.
Additional Tips to Keep Your Cool
While troubleshooting and fixing your current AC is essential, here are some additional tips to improve your cooling experience and potentially prevent future short cycling issues:
Upgrade Your AC
If your AC unit is old, inefficient, or constantly requires repairs, consider upgrading to a newer, more energy-efficient model. Modern AC units often come equipped with advanced features like variable-speed compressors, which can adjust their output based on cooling demand, thus minimizing short cycling and saving energy. According to the U.S. Department of Energy, replacing a 10-year-old AC unit with a newer, ENERGY STAR-certified model can reduce your cooling costs by 20%.
Smart Thermostats
Smart thermostats offer a range of features that can help prevent short cycling and optimize energy usage. They can learn your cooling preferences and adjust settings automatically based on your schedule and occupancy patterns. Some models even offer remote access, allowing you to control your AC from your smartphone. A study by Nest Labs found that their smart thermostat users saved an average of 10-12% on heating and 15% on cooling bills.
Energy-Saving Tips
Reducing your reliance on air conditioning can lower your energy bills and lessen the strain on your AC unit, potentially preventing short cycling. Here are some tips:
- Shade your windows – Use curtains, blinds, or awnings to block direct sunlight and reduce heat gain in your home.
- Improve insulation – Proper insulation prevents cool air from escaping and warm air from entering, reducing the workload on your AC.
- Use fans – Ceiling fans or portable fans can create a cooling breeze and make you feel more comfortable at higher thermostat settings.
- Seal air leaks – Check for gaps around windows, doors, and ductwork, and seal them to prevent air leakage.
Implementing energy-saving measures and addressing short-cycling issues can significantly reduce cooling costs and environmental impact. Remember, a well-maintained AC unit is more reliable and cost-effective in the long run. Visit https://leethompsonac.com/home-comfort-plans/ or give us a call anytime at (713)766-4846 to learn more and sign up.
The Bottom Line
If your AC is still cycling on and off after trying these steps, it’s probably time to bring in the experts. Since 1961, The Lee Thompson Co. has been Houston’s go-to HVAC team, known for solving even the toughest cooling challenges.
Don’t let a finicky AC ruin your comfort—contact us for prompt and professional service anytime at (713)766-4846. We’ll get your system running efficiently again, so you can stay cool and comfortable no matter how hot it gets outside.
