Why Is My AC Not Cooling Properly?
There’s nothing worse than a hot day in Chicago and a home that won’t cool down. If your air conditioner is running but the house still feels warm, you’re probably wondering what’s going on—and whether it’s something serious.
Good news: in many cases, it’s a simple fix. From dirty filters to thermostat mix-ups, there are plenty of reasons your AC might not be keeping up. Shavitz Heating and Air Conditioning will walk through the most common ones, what they mean, and what you can do to get your cool air flowing again.
1. Dirty or Clogged Air Filter
How do air filters cause an AC to not cool properly?
Your AC filter’s job is to trap dust, dirt, and debris, but when it gets too full, it can actually block airflow. That makes it hard for your system to cool your Evanston, IL, home properly.
Between bills, busy schedules, and keeping up with daily life, it’s easy to forget about filter changes. Believe me—we get it! That’s why we always check and change your filter as part of our routine maintenance visits.
Need a filter change between visits? No problem. We’ve got you covered with quick, easy service when you need it; just ask one of our techs during our next visit!
Why does changing air filters matter?
When airflow is restricted, your AC has to work harder and cool less efficiently. That means higher energy bills, uneven temps, and more wear and tear on your system.
What to do about dirty air filters?
Check your air filter. If it looks dirty or dusty, swap it out! Aim to change it every 1–3 months, depending on how often your system runs (and whether you have pets or allergies).
Regular maintenance keeps your system running smoothly—and helps prevent bigger problems down the road.
For more info on filter types and replacement schedules, check out our guide: How Often Should You Replace Your HVAC Air Filter?
2. Low Refrigerant Levels
How does a low refrigerant level cause an AC to not cool properly?
Refrigerant is the fluid responsible for absorbing heat from your Evanston, IL, home’s air and releasing it outside. If your AC is low on refrigerant, it won’t absorb heat effectively, and the system won’t cool as efficiently.
Why does proper HVAC refrigerant level matter?
Low refrigerant usually indicates a leak in your system. Refrigerant doesn’t get used up during normal operation—it leaks out, which requires professional attention. Running your AC with low refrigerant forces it to work harder, which can lead to costly damage, especially to the compressor.
What to do if the HVAC refrigerant is low?
If you notice your AC isn’t cooling or is constantly running without lowering the temperature, it’s time to give Shavitz a call. Our technicians can locate the leak, fix it, and refill the refrigerant to the proper level. Don’t wait—running your AC with low refrigerant can cause expensive damage to your system.
3. Dirty HVAC Coils
How do dirty HVAC coils cause an AC to not cool properly?
Your AC has two sets of coils: the evaporator coil (inside) and the condenser coil (outside). Over time, both can accumulate dirt and debris, reducing their ability to absorb and release heat.
Why do clean HVAC coils matter?
Dirty coils prevent the system from efficiently transferring heat, leading to poor cooling and potential overheating.
What to do about dirty HVAC coils?
While you can clean debris around the outside unit, the coils themselves need professional cleaning. Schedule annual maintenance with an HVAC technician to ensure your system is performing at its best.
4. Frozen Evaporator Coils
How do frozen HVAC coils cause an AC to not cool properly?
If your evaporator coils freeze, your AC can’t absorb heat, causing the system to blow warm air. This is usually caused by poor airflow (such as a clogged filter) or low refrigerant.
Why does repairing frozen HVAC coils matter?
Frozen coils stop your AC from cooling effectively, leaving your home warm and uncomfortable.
What to do about frozen HVAC coils?
Turn off your AC to allow the coils to thaw (this could take several hours). Once thawed, check the filter and replace it if necessary. If the issue persists, contact an HVAC technician to inspect and fix the underlying cause.
5. Thermostat Issues
How do thermostat issues cause an AC to not cool properly?
Sometimes the issue lies with your thermostat, which may be malfunctioning or improperly calibrated.
Why does fixing thermostat issues matter?
A faulty thermostat can cause your AC to turn on and off at the wrong times, leading to inconsistent temperatures.
What to do about thermostat issues?
Check the thermostat settings and ensure it’s in cooling mode at the correct temperature. If it’s still malfunctioning, try changing the batteries (if applicable) or recalibrating it. If that doesn’t help, replacing the thermostat may be necessary.
6. Leaky Ducts
How do leaky ducts cause an AC to not cool properly?
If there are leaks or blockages in your ductwork, cool air won’t be properly circulated throughout your home.
Why does repairing leaky ducts matter?
Leaky ducts waste cool air, making your AC work harder to maintain the desired temperature and reducing efficiency.
What to do about leaky ducts?
If you suspect leaks in your ducts, contact a professional to inspect and repair them. Sealing ducts improves airflow, overall system efficiency, and indoor air quality.
7. Improperly Sized AC Unit
How does an improperly sized AC unit cause it to not cool properly?
If your AC unit is too small for your home, it will struggle to cool effectively. If it’s too large, it may short-cycle, wasting energy and wearing out the system faster.
Why does proper AC sizing matter?
An improperly sized unit won’t perform efficiently, leading to discomfort and higher energy costs.
What to do about an improperly sized AC unit?
Have an HVAC technician perform a load calculation to ensure your AC unit is appropriately sized for your home. If necessary, they can help you choose and install a new system.
8. Your AC Might Just Be Past Its Prime
How does old age cause an AC unit to stop cooling properly?
Like anything else, air conditioners don’t last forever. If your unit is over 10 to 15 years old, chances are it’s not cooling as well as it used to—and it’s probably working a lot harder to do the job.
Why does the age of an AC unit matter?
Older systems tend to break down more often, run less efficiently, and cost more to operate. Plus, outdated models often lack the energy-saving features and technology that come standard in today’s systems.
What can you do about an older AC unit?
If you’ve had to call us out more than once this season, your AC might be hinting that it’s ready for retirement—and we’re here to help you plan the next step. That doesn’t mean you have to make the leap today—but it’s a good idea to get an honest assessment from a trusted technician.
At Shavitz, we’ll take a look at your system, talk through your options, and help you decide whether a repair or replacement makes the most sense for your home, comfort, and budget. No pressure—just the info you need to make the right call.
AC Not Cooling? Get Expert Air Conditioning Repair in Chicago
If your air conditioner isn’t cooling properly, understanding the cause is key to getting it back in top shape. Whether it’s a dirty filter, low refrigerant, or a worn-out unit, timely repairs and maintenance can help restore comfort to your home. If you’re unsure or need professional help and are in the greater Chicago metropolitan area, don’t hesitate to contact the best local HVAC company: Shavitz!
Call Shavitz Heating and Air Conditioning
Contact us today to schedule an AC inspection or repair, or for more tips on keeping your Evanston, IL, home cool and comfortable all summer long! Call Shavitz Heating and Air Conditioning or request service online.