Nothing is more frustrating than walking into your home on a hot St. Louis day only to realize your air conditioner is running but not blowing cold air. The good news is that some cooling problems have simple fixes.
Key Takeaways
- Start with the simple fixes, like checking the air filter, thermostat, and circuit breaker.
- Common problems that require professional HVAC services include frozen coils, refrigerant leaks, and compressor issues.
- Regular maintenance is one of the best ways to prevent unexpected AC breakdowns and extend your system’s lifespan.
How to Troubleshoot an AC Not Blowing Cool Air
A broken AC is frustrating, but it often has a simple fix. Before dialing for service, take a few quick troubleshooting steps to see if the issue is easy enough to fix on your own.
Look at the Air Filter
A dirty air filter is one of the most common reasons an AC stops blowing cold air. When dust, pet hair, and other debris clog the filter, airflow becomes restricted. Without enough airflow, your system can’t remove heat effectively. Over time, this buildup may even freeze your system’s evaporator coils (which can be a costly repair).
That’s why if your AC is running but not blowing cool air, we recommend checking the air filter first. Locate your system’s air handler and pull out the filter. If it looks dirty, replace the filter with one that matches your system’s specifications (both in terms of size and SEER or MERV rating, which should be on the filter itself).
Tip for Homeowners: Check your filter frequently. Depending on your system, your filters may need replacing every 1 to 3 months to keep it running smoothly.
Double-Check the Thermostat Settings
If a dirty filter isn’t to blame for your air conditioning woes, move on to your next step: checking the thermostat settings.
When checking your thermostat settings, see if:
- The thermostat is set to Cool.
- The temperature is set below the current room temperature.
- The fan is set to Auto instead of On.
- The batteries (if applicable) still have power.
Sometimes a thermostat is accidentally switched to the wrong setting, especially during seasonal weather changes or after a power outage.
“Turn It Off and Turn It Back On”
Sometimes the solution really is that simple.
If your AC suddenly stops cooling, check your home’s electrical panel to see if the air conditioner breaker has tripped.
If the breaker has not tripped, it usually indicates another issue.
If the breaker has tripped, try the following:
- Turn the breaker completely off.
- Wait a few seconds.
- Flip it back to the on position.
If the breaker trips again shortly after completing these steps, don’t continue resetting it. That’s usually a sign of an electrical issue or equipment failure that an HVAC technician should inspect.
Take a Look at the Evaporator Coils
Evaporator coils live inside your HVAC’s air handler or furnace and absorb heat from your home’s air. If these coils become dirty, they can’t transfer heat efficiently. If they freeze, airflow may stop almost entirely. In other words: two common problems with these coils can be a drop in your home comfort.
If the previous troubleshooting steps don’t work, check the evaporator coils.
To start, access the coils and see if they are dirty. If they appear dusty, turn off the system and carefully clean them according to your owner’s manual. If the coils are frozen, turn the system off. Then, schedule professional service.
Frozen evaporator coils often result from airflow problems, refrigerant leaks, and other issues that require professional diagnosis and repair.
Examine the Outdoor Condenser Unit
Your HVAC’s condenser unit sits outside the home; it releases heat that the system removes from the home. When airflow around the unit becomes restricted, cooling performance suffers.
Before going any further, make sure you turn the power off before inspecting the unit.
Once the power to your outdoor condenser unit is off, you may be able to try a few quick fixes like:
- Removing leaves and grass clippings around the unit.
- Gently rinsing dirt from the condenser coils using a garden hose.
- Trimming vegetation to maintain several feet of clearance around the equipment.
If the fan isn’t spinning properly or you suspect the compressor has failed, leave the system off and contact an HVAC professional. Compressor repairs require specialized equipment and training.
Check the Air Ducts
Even if your air conditioner is producing cold air, damaged ductwork can prevent that cool air from reaching your living spaces. So when all else fails, check your ductwork for leaks.
Specifically, inspect any accessible ductwork for:
- Loose connections
- Visible gaps
- Torn flexible ducts
- Air leaking around seams
If the leak is small, you may be able to seal it yourself with some HVAC foil tape. But for larger leaks, disconnected ducts, or damaged ductwork, leave the air duct repairs to the professionals.
Know the Signs It’s Beyond DIY-ing
Some AC problems aren’t safe or practical for homeowners to fix.
It’s likely time to schedule professional HVAC service if you notice:
- Ice forming on refrigerant lines or evaporator coils
- Hissing sounds
- Burning odors or electrical smells
- Loud grinding, banging, or squealing noises
- The outdoor compressor not starting
- Your AC repeatedly tripping the breaker
- Your system still not blowing cold air after trying basic troubleshooting steps
Signs It’s Time to Call Future Aire
When your AC isn’t working, your home’s comfort and health are on the line. And when you can’t diagnose and fix the problem quickly and safely on your own, leave your home in good hands.
Future Aire technicians service all major HVAC brands and can quickly diagnose most problems. In fact, our fully stocked service vehicles allow us to complete approximately 99% of repairs during the initial visit whenever possible. It’s the reliable, local service that your neighbors have trusted for years.
Preventing Future Breakdowns
No air conditioner lasts forever, but some simple preventive care can lower the odds of unexpected repairs.
Choose a Reputable Brand
The quality of your HVAC equipment matters. Systems from trusted manufacturers like Carrier are built for dependable performance and excellent energy efficiency. As a Carrier Factory Authorized Dealer, we’ve seen firsthand how quality equipment paired with proper installation can provide years of dependable comfort.
Schedule Regular Maintenance
Routine maintenance is a great investment in your HVAC system. Keeping up with maintenance can improve efficiency, reduce breakdowns, and help extend the life of your air conditioner.
Homeowners can help by changing filters regularly and keeping the outdoor unit clean, but professional tune-ups allow technicians to fix small issues before they become expensive repairs.
Get Back to a Comfortable Home Now
If your AC still isn’t blowing cold air after DIY troubleshooting, contact us right away. Our experienced technicians diagnose the cause quickly, explain your repair options, and get your cooling system back to work.
FAQs
Should I turn off my AC if it is not cooling?
Yes. It’s best to turn off any equipment if it isn’t functioning properly, whether you are attempting a DIY repair or hiring professional HVAC services. Continuing to run a malfunctioning system can sometimes cause additional damage or even put your safety at risk.
How do I reset my central AC if it is not blowing cold air?
Sometimes an AC isn’t working because a circuit breaker has tripped. If you believe a tripped breaker is the cause of your central AC not working:
- Go to your home’s electrical panel.
- Locate the switch for the AC.
- Flip back to the On position if the breaker was tripped
- If the breaker trips again, discontinue use and schedule professional service.
How can I tell if my AC is low on refrigerant?
Unlike other systems, an AC system isn’t a system where you can “fill up” on refrigerant. In other words, if your AC refrigerant levels are “low,” what it really means is that you have a refrigerant leak–and that is not something you can handle yourself. By law, handling certain types of refrigerant requires specific licensing.
As such, if you notice signs of a refrigerant leak–which includes ice buildup on copper wires or a “hissing” sound–you need to schedule service with a professionally licensed HVAC contractor.
Why is my AC not blowing out cold air in my house?
There are many reasons an AC won’t blow cold air throughout the home. Some of the most common reasons for malfunctioning air conditioning systems that we encounter in the St. Louis area include air filter issues, damaged air ducts, blocked condenser units, and refrigerant leaks.
