Why Is My AC Blowing Warm Air? AC Troubleshooting Tips

On a hot, muggy Midwest day, there is no better relief than an air-conditioned home. 

Your home is your retreat from scorching temperatures and stifling air. But what happens when the refreshing blast of air you rely on for comfort becomes a weak, lukewarm puff? 

Although disappointing and uncomfortable, your AC blows warm air for a reason, and at Midwest Air Pros, we are here to help you understand why and what you can do about it. 

Midwest Air Pros is your go-to online platform for finding local HVAC experts in Iowa, Kansas, Missouri, and Nebraska. We are proud to work with York dealers and help you connect with an AC professional you can trust. Click our Find a Pro link to get started.

Before panicking about hefty repair bills, let’s walk through some common AC problems and consider DIY steps before calling for professional assistance. 

Low Refrigerant

Refrigerant is the crucial component of your AC system that absorbs heat from inside your home and releases it outdoors. If your air conditioner is low on refrigerant, it cannot cool your home effectively. You will likely feel a weak or warm airflow from your vents, hear a hissing or bubbling sound from the outdoor unit, or see ice buildup on the refrigerant line. 

Dealing with refrigerant is not a DIY job. It calls for the expertise of an HVAC professional. Only technicians certified by the U.S. Environmental Protection Agency (EPA) should check for leaks, repair them, and recharge the refrigerant. 

If you suspect your system is low on refrigerant, turn it off and contact one of our Midwest Air Pros network members. Running your system with low refrigerant can strain components like the compressor and lead to costly repairs. 

Dirty Air Filters

Your AC air filter traps dust, pollen, and other airborne particles, preventing them from moving through your home and AC system. When clogged, the filter restricts airflow, which can reduce cooling capacity and may even cause the evaporator coil to freeze. 

A dirty or clogged air filter could be why your AC blows warm air. A dirty filter is easy to diagnose. Turn off your AC, pull the filter out of its housing, and inspect it for dirt, dust, and clogs. Replace it with a clean filter if necessary. 

Filter replacement is one of the easiest and most important maintenance tasks you can do for your AC system. Read your manufacturer’s instruction book on filter change frequency. Some filters last a few months and some work for up to a year before you need to replace them. 

Thermostat Setting

A thermostat with low battery power or incorrect settings can cause your air conditioner to blow warm air. 

Correct thermostat settings might seem obvious, but homeowners can easily overlook them. Here is what you need to check: 

• Set the thermostat to cool, not heat.
• The thermostat setting must be lower than the room temperature for the air conditioner to kick on. 
• Set the fan to auto, not on. When set to on, the fan runs continuously, even when the compressor is not cooling, and the air it blows through vents may feel warm. 
• Some thermostat models use batteries. Be sure they are working. 

If the air from your AC system feels warm after you adjust the settings, the thermostat might need professional attention. 

AC Coil Trouble

Restricted airflow, often from a dirty air filter, can cause the evaporator coil inside your home to freeze. A layer of ice prevents the coil from absorbing heat. If this happens, you might notice little to no air coming from vents. The fix is to turn off your AC and call a professional for a diagnosis and repair.

A dirty or blocked condenser coil could also be the culprit. It will not release heat effectively if debris or foliage is in the way and obstructing airflow. Remove shrubs, tall grass, overhanging branches, and other obstructions within a couple of feet of the outdoor unit. 

Now, what about dirt and signs of damage? Turn off the power and gently rinse the outdoor coils to remove dirt. Next, examine the aluminum fins attached to the outdoor coils for signs of damage. 

The U.S. Department of Energy (DOE) says regularly maintaining the fins helps your AC system operate efficiently. It points out that HVAC experts use a simple fin comb to straighten and adjust bent fins.

If you notice damage to your outdoor unit, contact one of our Midwest Air Pros directory members for AC diagnosis and repair.

Leaky Ductwork

Ductwork is the distribution system for conditioned air in your home. If your AC works efficiently, it sends cool air through the ducts and out your room air vents. If your ducts have holes, cracks, or poor connections, the refreshing air escapes into your basement, attic, or between the walls.

Your system may seem to underperform because the conditioned air does not reach your living space. If some rooms are cool and others are warm, the problem likely involves your ductwork. 

AC Maintenance

An annual professional AC tune-up can prevent minor issues from escalating into major ones, saving you from a costly breakdown. In one annual visit, an HVAC expert can test the refrigerant level, check coils, ensure the thermostat works correctly, examine your ductwork, and inspect and clean major AC components.

Schedule AC maintenance to prevent your system from blowing warm air on hot summer days. You will gain peace of mind knowing your air conditioner will keep you comfortable even during a heat wave.

Find a Trusted York Dealer Today

Midwest Air Pros makes finding a local HVAC professional in Iowa, Kansas, Missouri, and Nebraska easy. All companies listed on our site are trusted York dealers with a reputation for quality service, expert diagnosis, and reliable repair.

Stay cool this summer with Midwest Air Pros. Find a York dealer near you by clicking our link.