Why Is My AC Running But Not Cooling?( Top 5 Causes Homeowners Should know)
When your air conditioning is running but not cooling, it’s not just frustrating, it can be expensive and uncomfortable. As temperatures rise in Texas, the last thing you want is warm air blowing through your vents while your energy bill climbs.
Here are the top 5 reasons your AC might be running but not cooling, and what you can do about it.
1. Dirty Air Filter
A clogged air filter restricts airflow and can make your system overheat and shut down early — or just blow lukewarm air. This is one of the simplest issues to fix, and it’s often the most overlooked.
Pro Tip: Check and replace your air filter every 1–3 months (1” filters) and 6-12 months( 4”-5” Filters), especially during peak season.
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2. Frozen Evaporator Coil
If your system isn’t getting enough airflow (due to a dirty filter or defective blower motor), has significantly low refrigerant charge or a restriction in the refrigerant cycle, the evaporator coil can freeze over. When this happens, your system will keep running, but it won’t cool the air at all.
Warning sign: Ice or frost buildup on the refrigerant lines near your indoor unit and if significant enough all the way to your outdoor unit sometime all the way to the internal Compressor.
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3. Low Refrigerant Levels
Refrigerant doesn’t just “run out” or “get consumed by the system like fuel in a car” — if levels are low, you likely have a leak. This reduces your system’s ability to absorb heat from your home, leaving you with warm air even though the unit is technically running.
Pro Tip: If your AC seems to work fine sometimes and then weakens, or if your energy bills are creeping up, a refrigerant issue might be to blame.
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4. Outdoor Unit Is Blocked or Dirty
Your outdoor condenser unit needs room to breathe. If it’s covered in leaves, dirt, or grass, or if the coil is coated in grime, it can’t release heat properly. That means your system can’t finish the cooling cycle, even though it’s running full speed.
Check: Make sure there’s at least 2–3 feet of clearance around your outdoor unit, ( most manufactures allow for one side to have 6” of clearance on one side, typically the side facing the home") and that it’s clean and free of debris. Most modern day condensers are equipped with pressure safety controls for added protection, in the event the unit can’t breathe this will cause pressure to elevate and in extreme cases shut down the unit and short cycle.
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5. Thermostat or Electrical Issue
Sometimes the problem isn’t mechanical — it’s your thermostat not sending the right signals, or an electrical component inside the unit (like a contactor or capacitor) not working properly. A tripped breaker due to power surging etc. These small items/components need to be checked regularly to ensure proper operation and in many cases maintain the systems manufactures warranty.
If your system clicks but doesn’t cool, or cools for a minute then stops, this could be the issue.
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What Should You Do Next?
If you’ve checked the filter and thermostat, and your AC is still running but not cooling, it’s time to call a pro.
At Top Notch Heating and Air, we specialize in fast, honest diagnostics. We’ll tell you exactly what’s wrong, fix it right the first time, and make sure you’re not stuck sweating through another Texas summer.
