When the summer heat rolls in, one of the most common calls Lambton Heating and Cooling receives is about an AC not cooling. The unit might be running, but instead of delivering refreshing, cool air, it’s barely making a difference.
While there are several possible causes, one of the most frequent issues our technicians find is a worn or failing capacitor — a small part that plays a big role in your comfort.
The Importance of a Capacitor in Your Air Conditioner
Inside your AC system, the capacitor acts like a temporary battery. It stores and releases an electrical charge to get the compressor and fan motors started, then helps keep them running.
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Start capacitors provide the initial burst of energy to start the system.
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Run capacitors supply steady voltage to keep things moving.
If a capacitor wears out, the AC can hum but won’t start, blow warm air, or shut down mid-cycle — all signs of an AC not cooling effectively.
Why Heat and Heavy Use Cause More AC Problems
Summer puts your AC under intense strain. Here’s why capacitor issues and other cooling problems become more common during hot months:
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High outdoor temperatures – Excess heat accelerates wear and can cause electrical components to overheat.
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Longer run times – The hotter it is, the longer your AC runs, putting more stress on every part.
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Age of the system – Capacitors typically last 5–10 years, and older systems are more likely to fail under heavy summer use.
Warning Signs Your Capacitor Could Be the Problem
If your air conditioner is struggling, these symptoms could point to capacitor trouble:
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AC starts slowly or not at all
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Warm air blowing from vents
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Random shut-offs during operation
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A loud humming from the outdoor unit
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Bulging or leaking on the capacitor casing
According to Trane’s troubleshooting guide, weak airflow and unusual noises can be early indicators that your cooling system needs immediate attention.
Preventing an AC Not Cooling Situation
You can’t stop every breakdown, but you can lower the risk with proactive care:
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Book an annual AC tune-up before the heat arrives
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Keep your outdoor condenser unit free of leaves, grass, and dirt
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Change air filters regularly to maintain proper airflow
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Upgrade older parts before they fail
Other Reasons Your AC Might Not Cool
Capacitors aren’t the only cause. Your AC may also be underperforming due to:
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Refrigerant leaks
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Dirty coils reducing heat transfer
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Clogged air filters
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Malfunctioning thermostats
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Failing compressors
As Lennox explains, poor cooling can also be caused by airflow restrictions, blocked vents, or sensor issues that prevent your system from running at peak efficiency.
A certified technician can pinpoint the cause of an AC not cooling and fix it quickly to restore comfort.
Get Your Cooling Back On Track
If your AC is not cooling and you’re feeling the heat, don’t wait until
it fails completely. Lambton Heating and Cooling provides fast, reliable service to keep your home comfortable — whether it’s a capacitor replacement, refrigerant recharge, or full system inspection.
Contact Lambton Heating and Cooling
📞 Call: 519-344-5521
📲 Text: 226-210-3478
🌐 www.lambtonclimatecare.com
📧contact@lambtonclimatecare.com
