Why Is My Air Conditioner Blowing Hot Air?

When your air conditioner randomly starts blowing warm air rather than cold, that can be a bit alarming. Fortunately, AC units that blow warm air are fairly common, and they’re relatively simple to diagnose.

What might be causing your air conditioner to blow a bit too warm for your taste? Read on to learn all about the top four most common culprits and our best recommendations for addressing the problem.

1. Your Thermostat Is Set Incorrectly

When your air conditioner appears to be blowing warm air, and you’re unsure why, the first thing you should do is check the temperature setting of your thermostat. If the thermostat is set to “heat” rather than “cool,” it will end up blowing air that’s warmer than you’d like.

If your thermostat is on the appropriate cool setting, however, the issue may be the fan setting. When your fan is set to “on,” it will continue to blow air into your home even when your AC unit is not actively cooling air. That air will end up being warmer than you’d like since the outdoor unit is not actively circulating the refrigerant that absorbs heat from the incoming air.

When your fan is set to “auto,” on the other hand, it will automatically stop running when your outdoor unit is not actively circulating refrigerant. If you only want cool air to blow into your living spaces, make sure your fan is set to “auto.”

If your thermostat setting appears to be correct, but your AC is still producing warm air, your thermostat could also be faulty, in which case you’ll likely need to have it replaced.

2. Your Outdoor AC Unit Lost Power

Do you have central air-conditioning? If so, your AC system consists of two units. One of those units — the indoor component — blows cool air into your ductwork, which then travels into your home. The other unit — the one you see outdoors with the large fan — is designed to remove heat from the air before funneling it toward the indoor unit that blows the air into your home.

If the outdoor unit loses power for any reason, it will not be capable of cooling down air since it must have power to circulate the refrigerant that absorbs heat energy from the air. Ultimately, any air that circulates through your air ducts and into your living areas will end up being warm.

How do you fix this issue? Check your electrical breaker box or fuse box for a tripped breaker or blown fuse. If you can see that the breaker or fuse that controls your outdoor AC unit has tripped or blown, you can reset the breaker or replace the fuse and check to see if that solves the problem. If it doesn’t, call an air conditioner repair specialist for a comprehensive unit inspection and diagnosis.

3. The Air Conditioner’s Evaporator Coil Is Dirty

The outdoor component of your air conditioner contains an evaporator coil, which houses the refrigerant that cools down the air before it travels into your home. When that coil gets too dirty, the refrigerant within it cannot properly cool the air as it passes through the coil. And that too-warm air will ultimately travel into the indoor unit that funnels it through your air ducts and into your home.

If you suspect a dirty evaporator coil is causing your air conditioner to blow warm air, call an AC repair specialist who can verify what the true culprit is. If it is indeed the evaporator coil, a thorough cleaning should solve the issue. From there, be sure to change your HVAC filter regularly as dirty filters can contribute to excessive debris buildup on the coil.

It’s also a good idea to have your outdoor AC unit cleaned annually to ensure the coil remains free of excessive buildup. You can perform this job yourself, but if you’re unsure how to do it, it’s probably in your best interest to leave the job to a pro.

4. Your Unit Is Low on Refrigerant

If you own an older AC unit, a refrigerant leak may be the culprit behind your warm air issue. When there’s not enough refrigerant in your AC unit, it’s impossible for the unit to cool down incoming air, so until you have the refrigerant topped up, your AC will continue blowing warm air.

If you suspect low refrigerant levels are causing the problem, the first thing you’ll need to do is identify whether your AC unit has a leak. Not sure how to do that? Call an AC repair specialist who can locate the leak, repair it, and recharge your air conditioner.

Need AC Repairs in Dallas or Fort Worth? Call Metro Express Service

If your air conditioner appears to be acting up, don’t hesitate to call our team at Metro Express Service for expert help. We offer 24/7 emergency service, and our AC technicians can thoroughly inspect your unit to identify, diagnose, and repair any problems it may have. If your unit is having issues because it’s reaching the end of its functional life, we can also perform a complete AC replacement if opting for a new unit is your most cost-effective option.

To learn more about our services or schedule an appointment, feel free to give us a call today at 817-516-0700 (Arlington/Fort Worth) or 972-263-2500 (Dallas). You can also contact us online with any questions or concerns, and we’ll be in touch promptly.


Randy Murphy

Randy Murphy has been building his knowledge of the air conditioning and heating business for several years now. He first started applying his knowledge while working for his father’s HVAC company. Later, in 1987, Randy started his own business: Metro Express Service. He has been a top 10 Trane & Amana dealer for over eight years. When it comes to heating and cooling, Randy knows the business better than anyone.
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