Why Is My AC Blowing Hot Air?
August 15, 2025
It’s a hot day outdoors in Boone, and you’re inside your home waiting for your air conditioning (AC) system to kick into full gear.
But instead of cool air flowing from your vents, all you feel is warm—maybe even hot—air!
Few things are more frustrating than an air conditioner malfunctioning in the middle of summer. When your AC isn’t doing its job, it can feel like your whole home is under pressure. Luckily, Neighbors is here to help keep you from overheating.
Whether the issue is simple or more complex, you can leave your heating and cooling concerns to our experts. We’ll diagnose the problem and get your system back to peak performance. All you have to do is sit back and relax!
Reasons Why Your AC May Be Blowing Hot Air
Why is your air conditioner blowing out warm air when it should be keeping you cool inside your Iowa home? Here are some common reasons:
Your Thermostat Is Set Incorrectly
It sounds obvious, but it happens more often than you’d think—your thermostat may be set to Heat instead of Cool. Double-check the settings to make sure your system is set to the right mode.
Also, check the fan settings. Many thermostats allow you to switch the fan between AUTO and ON. During especially humid days in Boone, setting the fan to ON can help lower indoor humidity and improve indoor air quality (IAQ). Just remember, in the ON setting, the fan runs continuously—even when the AC isn’t actively cooling.
Your Refrigerant Is Leaking
Refrigerant is the chemical that cools the air your system blows into your home. If your system is low on refrigerant—due to a leak—it can’t cool the air properly. You may notice the AC running constantly but not lowering the temperature, or warm air blowing through the vents.
Low refrigerant isn’t something you can fix yourself. In fact, it’s best left to certified HVAC professionals. Contact Neighbors to inspect and recharge your system. If there’s a leak, we’ll locate and repair it before adding the correct amount of refrigerant.
Your AC Filter Is Clogged
A dirty or clogged air filter restricts airflow to your system, making it harder for your AC to circulate cool air throughout your home. Over time, this added strain can reduce efficiency, increase wear and tear, and even cause warm air to blow from your vents.
To keep things running smoothly:
- Replace disposable filters every 30–90 days.
- Clean reusable filters monthly.
- Check your filters more often during peak cooling season.
Want better air filtration? Consider upgrading to a high-efficiency filter. According to the EPA, HEPA filters can trap 99.97% of dust, pollen, mold, and other particles as small as 0.3 microns. Just make sure your HVAC system is compatible—some filters may restrict airflow too much if your system isn’t designed for them.
Your Evaporator or Condenser Coils Are Dirty
Your AC system has two types of coils that are essential for cooling: evaporator coils inside your indoor unit and condenser coils in the outdoor unit. Over time, both can accumulate dirt and grime, especially if regular maintenance has been skipped.
Dirty coils reduce your system’s ability to absorb and transfer heat, which can lead to:
- Warm air is blowing from the vents
- Ice forming on the coils or the condenser unit
- Higher energy bills
- Risk of system breakdown
Our Neighbors technicians can clean your coils safely and thoroughly, restoring your system’s efficiency and comfort. Routine coil cleaning and maintenance can also extend the life of your AC system.
Bonus AC Repair Tip: Check the Circuit Breaker
Sometimes, your air conditioning issue isn’t mechanical—it’s electrical. If your indoor unit is working but the outdoor condenser isn’t turning on, check the circuit breaker. If it has tripped, reset it. If the breaker keeps tripping, there could be an underlying electrical issue that requires professional attention.
Don’t Forget Preventative Maintenance
Preventative maintenance is key to avoiding issues like these. When you schedule a seasonal AC tune-up, our experts will inspect, clean, and test your system to ensure everything is operating at peak performance. Routine service helps catch small problems before they turn into expensive repairs—or total system failures.
If your system is older or has needed frequent repairs recently, this could also be a sign it’s time to start considering a replacement. Our Neighbors team can help you weigh your options and choose an energy-efficient model that meets your comfort and budget needs.
Our Air Conditioning Experts Are Here for You
No matter what’s causing your Boone, home’s air conditioner to blow warm air, Neighbors is here to help. From basic fixes like clogged filters and incorrect thermostat settings to more complex issues like refrigerant leaks and coil problems, we’ve seen—and solved—it all.
We’re proud to be your trusted HVAC professionals in Boone County and surrounding areas. Give us a call at Neighbors Heating and Cooling or request service online to schedule your AC repair or inspection. Let us help you get back to comfort—fast.