Why Does My AC Unit Turn On and Off? (Short Cycling Explained & Fixed!) 

Imagine this—you’re finally relaxing after a long summer day in Ontario, and suddenly, your AC unit turns on and off. One minute it’s cooling, the next it’s off. Then it’s back on again. This annoying on-and-off behavior, known as short cycling, isn’t just a minor inconvenience—it can increase your energy bills, damage your AC unit, and lead to costly repairs.
If your air conditioner turning on and off is becoming a frequent issue, don’t ignore it. This guide will walk you through the most common causes of AC unit turning on and off and how to fix them before they escalate into major HVAC issues.

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   Your Thermostat Is in a Bad Spot

Think of your thermostat as your AC’s brain—it tells the system when to turn on and off. But if it’s placed in the wrong location, it can misread temperatures and trigger unnecessary cycles. 

Bad Thermostat Placement: 

✔️ Near windows or direct sunlight – Makes the thermostat think your home is hotter than it actually is.
✔️ Close to supply vents – CCauses the AC unit turns on and off too soon.
✔️ Near heat-producing appliances – Confuses the system with false temperature readings. 

Fix: 

Relocating your thermostat to a neutral, central location can improve accuracy and stop short cycling.

2. Your AC Unit Is Too Big for Your Home

Bigger isn’t always better—especially when it comes to air conditioners. If your AC system is oversized, it cools your home too quickly and shuts off before completing a full cooling cycle. This leads to: 

❌ Uneven cooling across your home.
❌ Higher energy bills due to frequent restarts.
❌ Increased wear and tear on internal components. 

Fix: 

If your system is too large, a technician can install a variable-speed AC unit or adjust settings to improve efficiency. 

3. Dirty Air Filters Are Choking Your System

Your air filter is like the lungs of your HVAC system. If it’s clogged with dust, pet hair, or debris, it blocks airflow, making your AC unit turns on and off repeatedly as it struggles to function properly.

Signs of a Dirty Air Filter: 

✔️ Weak airflow from vents.
✔️ Higher electricity bills.
✔️ Increased dust in your home. 

Fix: 

Replace your air filters every 1-3 months—especially during peak cooling seasons. 

4. Refrigerant Leaks = Pressure Problems

Refrigerant (also called Freon) is the lifeblood of your AC. If you have a leak, your system will experience low pressure, triggering the compressor to turn off and on frequently.

Warning Signs of a Refrigerant Leak: 

🚨 Warm air coming from vents.
🚨 Hissing sounds near the AC unit.
🚨 Ice buildup on refrigerant lines. 

Fix: 

Refrigerant should only be handled by certified HVAC technicians. If you suspect a leak, call LG Home Comfort for professional AC repair in Ontario.

5. Frozen Evaporator Coils Are Shutting Your AC Down

If your evaporator coils freeze, your AC keeps turning on and off, struggling to cool properly.

What Causes Frozen Coils? 

❄️ Low refrigerant levels.
❄️ Clogged air filters.
❄️ Blocked or dirty evaporator coils. 

Fix: 

1️⃣ Turn off your AC immediately to prevent further damage.
2️⃣ Check and replace dirty air filters.
3️⃣ Call an HVAC expert if ice keeps forming. 

6. Your AC’s Electrical System Is Acting Up

Loose wiring, faulty sensors, or failing capacitors can cause your AC turns on then off randomly. Electrical problems can also increase fire hazards, so they shouldn’t be ignored.

Fix: 

⚡ Never attempt DIY electrical repairs—always call a licensed technician to diagnose and fix wiring or capacitor issues. 

7. Your Outdoor Unit’s Condenser Coils Are Filthy

Your condenser coils (located outside) release heat from your home. If they’re covered in dirt, pollen, or debris, they’ll struggle to expel heat, causing your air conditioner turn on and then off  immediately due to overheat. 

Fix: 

🌱 Keep vegetation at least 2 feet away from your outdoor unit.
🛠️ Schedule annual HVAC maintenance to keep coils clean and efficient. 

How to Prevent Short Cycling (AC Maintenance Tips!) 

Regular AC maintenance can extend your unit’s lifespan, prevent costly breakdowns, and improve energy efficiency. Here’s what you can do: 

✔️ Change air filters every 1-3 months.
✔️ Schedule annual HVAC tune-ups with LG Home Comfort.
✔️ Keep vents unblocked to ensure proper airflow.
✔️ Clean your outdoor unit to prevent overheating.
✔️ Upgrade your thermostat to a smart model for better efficiency. 

Still Dealing With an AC That Won’t Stay On? Call LG Home Comfort! 

If your ac runs constantly at your home but now your air conditioner keeps shutting off, don’t wait until it completely breaks down. LG Home Comfort offers fast, reliable ac repairs across the Ontario, helping homeowners beat the heat with expert service.

✅ Licensed HVAC technicians with years of experience.
✅ Affordable, upfront pricing—no hidden fees!
✅ 24/7 emergency AC repair available. 

📞 Call us today at [Your Phone Number] or book an appointment online! 

Final Thoughts

Short cycling is more than just annoying—it can skyrocket your hydro bill, reduce your AC’s lifespan, and leave you sweating in the heat. Whether it’s a thermostat issue, airflow restriction, or refrigerant leak, identifying the root cause is key to fixing the problem for good.

By following these troubleshooting tips and scheduling routine HVAC maintenance, you can keep your AC unit turns on and off unexpectedly all summer long!  ☀️❄️

FAQ's

1. Why does my AC turn off after a few minutes?

Your AC may be short cycling due to a dirty air filter, refrigerant leak, thermostat issues, or an oversized unit. Regular maintenance can help prevent this problem.

2. Can a bad thermostat cause my AC to short cycle?

Yes, a poorly placed or malfunctioning thermostat can send incorrect temperature readings, making your AC unit turn off too soon or restart frequently.

3. How do I fix an AC that keeps turning on and off?

Check for clogged filters, frozen coils, refrigerant leaks, or electrical issues. If unsure, call a professional HVAC technician for a proper diagnosis.

4. Is short cycling bad for my air conditioner?

Yes, frequent on-and-off cycling increases energy costs, wears out components faster, and reduces your AC’s lifespan.

5. Can low refrigerant cause my AC to short cycle?

Absolutely! Low refrigerant levels lead to pressure imbalances, making the AC unit turn on and off unexpectedly. A professional recharge and leak repair can fix the issue.

6. When should I call an HVAC technician for short cycling?

If cleaning filters, adjusting the thermostat, or resetting the system doesn’t work, call an expert to prevent further damage and costly repairs.