AC Blowing Warm Air
After a long day at work, you’re tired, hot, and just want to relax in the comfort of your own home. But what happens if when you open your door, you’re greeted with a house full of warm air?
If your AC is blowing warm air, it’s a sign that something isn’t working as it should be. Luckily, there may be an easy fix you can do yourself.
8 Reasons Your AC Is Blowing Warm Air
Here are some of the most common reasons why your AC is blowing warm air and what to do next.
1. The Thermostat Is On the Wrong Settings
If your AC is blowing warm air, the first thing you should check is your thermostat’s settings because this will be the easiest fix.
It’s possible that someone may have accidentally switched the thermostat to OFF or ON instead of AUTO. Or maybe someone switched the thermostat to HEAT instead of COOL. If your thermostat is set to ON then the fan will blow air throughout your home even when your AC isn’t cooling the air, so be careful to check that this isn’t your issue.
Solution: Ensure that your thermostat is set to AUTO and COOL.
2. Clogged Air Filters
Can a dirty filter cause your AC to blow warm air? In extreme cases, yes.
One of the simplest ways to prevent your AC system from blowing warm air is to check and change your air filters regularly. Homeowners often neglect their AC system’s air filters even though they’re one of the most important. After you ensure your thermostat is on the correct settings, check if your air filters are dirty.
If your air filters are clogged due to excessive dirt, it can cause your AC system to blow warm air or stop blowing air altogether if it gets bad enough. A good rule of thumb is to change your air filter about once a month to keep your air conditioning system in top shape.
A clogged air filter can also lead to other issues that result in your AC system blowing warm air. The excess dirt and dust can start to collect on your AC’s components, such as the condenser coils, making them work harder than they should have to and eventually start to fail.
Solution: Check and replace your AC system’s air filter as needed.
3. Air Duct Leaks
If your air ducts have tears, kinks, holes, cracks, or become disconnected, air won’t circulate throughout your home as it should. Hot air can mix in with the cold air when it shouldn’t or the cold air may be escaping into your attic, walls, or crawl space.
Solution: It’s best to have an HVAC professional check your air ducts, as attempting to check yourself can result in further damage to already damaged ducts. An HVAC professional will also be able to tell you if it’s better to try to patch the ducts or replace them.
4. Dirty AC Condenser
Your AC condenser is the outside unit that removes the hot air from your home. If your condenser unit is dirty or surrounded by leaves and other debris, it can be hard for the unit to displace the hot air from inside your home. It also means your system isn’t functioning as efficiently as it could be. Cleaning your AC condenser can not only fix your problem now but also result in lower energy bills in the future.
Solution: To clean the condenser, turn off the unit at the thermostat and the breaker. Once the system powers down, remove any debris surrounding the unit and carefully hose down the coils and fins. You may also want to call a local HVAC company to clean the unit as part of an AC maintenance tune-up.
5. AC Condenser Not Turning On
After cleaning your AC condenser (the AC unit located outside), double check that the unit turns on. Your AC condenser is also responsible for cooling the air that circulates in your home, so if the rest of your AC system is running while your AC condenser is off, the air won’t be cooled.
Solution: Ensure that AC is set to on at the thermostat, that the breaker wasn’t tripped, or that someone forgot to turn the AC back on at the shut off switch. If your AC continues to trip the breakers or none of the above were the issues, you’ll want to have an HVAC company diagnose the issue as it could be the result of a failing part, such as the compressor or capacitor.
6. Dirty Evaporator Coils
Your air conditioner’s evaporator coils play a key role in the cooling process, so it’s important to keep them clean if you want your AC system to properly cool your home. If your AC’s evaporator coils are caked in dirt, it can result in multiple issues and inefficiencies, as well as cause your AC to blow warm air. Cleaning your AC’s evaporator coils may not only fix your issues now, but it can also result in lower energy bills in the future.
Solution: You can clean your evaporator coils yourself, but it may be time to schedule an AC maintenance or Tune-up if the coils are so dirty that they’re impeding your AC’s operation.
For more information, check out our article: How to Troubleshoot an AC That Won’t Turn On
7. Frozen Evaporator Coils
If you check your evaporator coils and find that they’re completely frozen, even in the summer, then you may have found the cause of your problem, or at least you’ll be closer to finding the root of the issue. Your AC’s evaporator coils cool the air, the coils contain cold refrigerant that removes heat from the air as it passes over them. However, if the evaporator coils are completely frozen over, then it could mean the hot air never actually passes over the coils and is never cooled. It may seem counterintuitive, a block of ice should certainly do a better job at cooling air than a cold coil, right? However, if your evaporator coils are freezing over, then it’s likely that the warm air never circulates around the coils, which is why the coils are freezing in the first place.
Solution: Unthaw your evaporator coils by turning off your AC or setting it to fan only. Once the evaporator coils are completely unthawed, try running your AC normally again to see if that fixes the problem. If that does fix the problem, but your evaporator coils freeze up again, you may want to contact an HVAC company to diagnose the problem, as it could mean that your system is low on or leaking refrigerant. You’ll especially want to have an HVAC technician diagnose this problem if you’ve already replaced the air filters and cleaned the unit, ruling those out as potential causes.
8. Refrigerant Leak
A refrigerant leak is one of the more serious issues that could cause your AC to blow warm air. Do not try fixing a refrigerant leak on your own.
Your AC system uses refrigerant to cool the air and then pumps the cooled air through your home. When refrigerant levels are low due to a refrigerant leak, your system cannot cool as efficiently as it could. If you also notice that your system is starting and stopping frequently, this could be a sign of a refrigerant leak.
Solution: If you suspect your AC is leaking refrigerant, contact an HVAC company immediately. Refrigerant can be dangerous and should be fixed by a certified technician.