At Sub Zero Temp Control, we hear this one a lot: “My ac unit is not blowing cold air—what’s going on?” If you’re dealing with this issue, trust us, you’re not alone. Whether it’s the dead of summer or just a warm spring afternoon, an AC that runs but doesn’t cool can quickly turn your home into a sauna. Fortunately, there are several common reasons this happens—and most are fixable with the right approach.
Let’s walk through the most likely causes and what you can do about them.
A Dirty Air Filter Can Lead to Your AC Unit Not Blowing Cold Air
One of the simplest reasons your ac unit is not blowing cold air is a dirty air filter. Yet, it’s also one of the most overlooked.
When the filter is clogged with dust, pet hair, and debris, it restricts airflow. This not only makes it harder for your system to cool your space but can also cause the evaporator coil to freeze up.
What to do:
Turn off your system and check the filter. If it looks dirty or hasn’t been changed in over 30 days, replace it. Most homeowners can do this themselves, but if you’re unsure, a technician can help during a routine maintenance visit.
For more on filter maintenance, check out this Energy Saver guide from the U.S. Department of Energy.
Low Refrigerant Levels Are a Frequent Culprit
Another big reason for an ac unit not blowing cold air is low refrigerant. Your AC relies on refrigerant to absorb and remove heat from the air. If it’s low, the system can’t do its job.
However, refrigerant doesn’t just disappear—it usually means you have a leak.
What to do:
You’ll need a licensed HVAC technician to locate and repair the leak, then recharge the refrigerant. This isn’t a DIY fix, as it requires proper tools and EPA-certified handling.
Learn more about refrigerant types and handling on EPA.gov’s refrigerant page.
Frozen Coils Might Be Why Your AC Unit Is Not Blowing Cold Air
When you notice your ac unit not blowing cold air, go take a peek at your indoor unit. Do you see any ice buildup? Frozen evaporator coils block airflow and cause the air to feel warm—or stop flowing altogether.
This can happen due to:
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Dirty filters
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Blocked ducts
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Low refrigerant
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Poor airflow
What to do:
Turn off the AC and let the coils thaw completely. Then check the filter and airflow. If it happens again, it’s best to call in a pro.
Malfunctioning Thermostat Settings
It might seem too simple, but the issue could be with your thermostat. If it’s not calling for cooling properly or is miscalibrated, your AC won’t cool.
What to do:
Double-check that it’s set to “cool” and the temperature is lower than the room temp. Also, check the batteries and settings. If you’re using a smart thermostat, make sure it’s connected and updated. For more insight into energy-saving thermostats and choosing the right one, take a look at this Energy Star thermostat guide.
Electrical Issues or Tripped Breakers
If the fan is running but the compressor isn’t kicking on, your ac unit not blowing cold air could be due to a tripped breaker or a faulty capacitor.
What to do:
Check your breaker panel for any tripped switches. Reset them and try again. If that doesn’t work, call a technician. Capacitor or compressor issues aren’t something to tinker with unless you’re certified.
Ductwork Problems Can Affect Air Temperature
Even if the AC itself is working, leaky or disconnected ductwork could be to blame for warm air. According to Energy Star, about 20-30% of cooled air can be lost through leaks, especially in attics and crawlspaces.
What to do:
Look for obvious gaps or disconnected sections. You can seal minor gaps with foil tape, but comprehensive duct sealing should be left to a professional.
When to Call an HVAC Professional
If you’ve tried the basics and your ac unit not blowing cold air persists, it’s time to call for help. An HVAC technician can:
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Diagnose refrigerant leaks
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Check electrical components
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Test airflow and ductwork
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Perform a full system tune-up
At Sub Zero Temp Control, we bring experience, high-end diagnostic tools, and a commitment to getting it right the first time. And we make sure every repair is done with your comfort and safety in mind.
How to Prevent AC Issues Going Forward
Here are a few tips that can help prevent your ac unit not blowing cold air in the future:
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Change your filters every 30 to 60 days
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Schedule seasonal maintenance to catch issues early
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Keep outdoor units clean and free of debris
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Install a programmable thermostat to reduce strain
Preventative care goes a long way toward ensuring your AC stays reliable all summer long.
Need Help With an AC Unit Not Blowing Cold Air?
Dealing with an ac unit not blowing cold air can be frustrating, but you’re not on your own. At Sub Zero Temp Control, we’re here to get your system running smoothly again—quickly and professionally.
We proudly serve Vancouver, WA and the surrounding areas. At Sub Zero Temp Control, we’ve helped plenty of local homeowners get their comfort back—and we’re happy to do the same for you. Whether you need AC repair, maintenance, or a full system replacement, contact us today for fast, expert service.
