Air conditioners are hard at work all day long. They battle the heat and humidity to keep your home comfortable. Like all mechanical equipment, problems are bound to happen from time to time. But many of these problems are simple DIY fixes. Some AC issues require a call to the professionals. Either way, knowing the problem can help you avoid costly repair bills.

Here are seven common air conditioner problems and how to fix them.

Problem #1: The AC Won’t Turn On 

This problem is incredibly frustrating. You press the button to turn on your AC. And nothing happens. Don’t freak out just yet. There are a few simple things to check first.

Look at the thermostat. Is it set to “Cool”? Is the temperature set lower than the current room temperature? Double check to make sure the AC is set to run.

If the thermostat settings are fine, check your electrical panel. A tripped circuit breaker is an easy fix. Just flip it back on and try again. If it trips immediately, call a technician. There could be a serious electrical problem. 

Don’t forget your thermostat batteries. If your thermostat is battery-powered, dead batteries could make it seem like the whole system has shut off. Replace the batteries and try again. 

Problem #2: AC Blowing Warm Air 

Warm air coming from your vents is a problem, especially on a hot day. First things first, check your air filter. One of the leading causes of an AC not cooling is a dirty air filter. Your filter blocks dust and debris from getting pulled into the system. If the filter gets too dirty, airflow is restricted. The system cannot operate properly without good airflow. Grab your filter and hold it up to a light. If you cannot see light coming through it, replace it.

If your filter looks good, you may have low refrigerant. Refrigerant is what cools the air as it passes through your system. The NHS told us that when there is a leak, your air conditioner will not cool properly. You may also see ice on the refrigerant lines leading into the unit, or on the outdoor unit itself. Refrigerant leaks cannot be fixed DIY style. You will need to call a licensed HVAC technician to repair the leak and recharge your system.

Problem #3: The AC is Frozen 

Ice on your air conditioner is counterintuitive, but it is not uncommon. Air conditioners can freeze up when the evaporator coil gets too cold. When this happens, moisture in the air freezes onto the coil. The ice blocks airflow and makes the system work harder.

Dirty air filters are often the cause. Running your AC on extra cold days can cause freezing. Low refrigerant can also freeze up your system. If you notice ice on your system, shut it off and allow it to thaw completely. This could take several hours. Once thawed, replace your air filter and turn it back on. If it freezes up again, you may have low refrigerant.

Problem #4: Short Cycling 

Short cycling is when your air conditioner never completes a full cooling cycle. The system turns on and off rapidly, never staying on long enough to cool your home properly. Cycling like this wastes energy and can damage your unit.

Short cycling has several causes. Dirty air filters and frozen coils can make your AC short cycle. Dirty condenser coils on the outside unit can also cause short cycling. Sometimes your air conditioner is simply too big for your space. An oversized air conditioner cools the room too quickly. It shuts off before it should and begins the cycle over.

Change your air filter first. Often that is all it takes. Next, wash down the outdoor unit to remove visible dirt. If the problem persists, call for service. A technician can confirm refrigerant levels and ensure you have the right size unit for your home.

Problem #5: Water Leak 

Water leaking from your air conditioner is never good. Air conditioners pull humidity out of the air as it cools. This water drains out of your system through the condensate drain line. Clogs in that line cause water to leak into your home.

Clear the condensate drain line yourself if you feel comfortable. Find the condensate drain pipe near your indoor air handler. Pour a solution of warm water and vinegar down the line to break up the clog. If the drain is severely clogged, you may be able to suck out the debris with a wet/dry vacuum. Set your AC to “Drain” if leaks continue. This will bypass the line and prevent water from entering your home. Finally, ensure the unit is level. If an air conditioner is tilted the wrong way, water will not drain properly.

Problem #6: Noise Coming from the Unit 

A properly functioning air conditioner should not make you jump out of your seat. If you hear banging, rattling, squealing, or clicking, take notice.

Rattling usually means something is loose. Inspect around your outdoor unit for debris that may have blown inside. Tighten any visible screws or panels you can access. If you hear a squealing noise, there could be a worn belt or a motor that needs lubrication. A slamming noise could be a loose or broken part inside the compressor. If you hear loud banging, shut off the unit and call a technician immediately.

Problem #7: Odors Coming from the Vents 

A musty odor coming from your vents is usually caused by mold or mildew buildup. Mold often grows in the drain pan or your ductwork. Replace your air filter and clean the drain pan with bleach and water. Call a professional to have the ductwork inspected if smell persists.

If you smell something burning, turn off your AC right away. Electrical problems can cause burning smells. A burning smell could also mean your motor is overheating. Do not ignore a burning odor. 

Case Study: Choosing Ductless AC Prevents Continued Problems 

The Smith family in Pennsylvania faced home comfort problems. Their central AC couldn’t keep them cool or dry during hot weather. Some rooms were always too hot and humid.

The family called an HVAC contractor for advice. The technician proposed installing a ductless mini-split with multiple indoor heads. After the new system was installed: 

• The Smiths had adjustable temperature control in every room
• They used less energy to cool their home efficiently
• Customer complaints about hot spots and humidity disappeared

This success story illustrates the importance of choosing the right AC system. Understanding the home’s needs and cooling demands prevents future headaches.

Find the full case study here: https://www.rfohl.com/case-studies/ductless-air-conditioner-installation-nesquehoning-pa/  

Air Conditioner FAQs: Troubleshooting and Maintenance 

My air conditioner is running but not cooling my home. What is the problem? 

Common reasons include low refrigerant, dirty filters or duct leaks, and even an undersized system. Start by replacing the filters and resetting the thermostat. If the AC still won’t cool, call an HVAC technician for diagnosis and repair.

How often should I change my air filter?

Typical replacement frequency is every 1–3 months. If you have pets or lots of dust, you may need to replace it more often. Clogged filters restrict airflow and cooling performance. 

I found a refrigerant leak with my AC. Can I just refill it? 

HVAC technicians need certification to handle refrigerants. Never try to refill your system yourself. Always hire a licensed professional to check for refrigerant leaks and safety hazards.

What causes short cycling and how can I correct it?

Dirty filters and frozen coils can cause short cycling. Also, if your air conditioner is too big for your home it cycles on and off. Try cleaning the indoor and outdoor units first. If it continues, call a technician to check refrigerant levels and the electrical motor.

Why is my AC freezing up? 

Refrigerant leaking onto the indoor coil will cause ice to build up. Other causes are restricted airflow from a dirty filter or setting the temperature too cold. Turn off the unit and let it thaw. Replace the filter and call for service if freezing occurs again.

There is water leaking from my air conditioner. What should I do? 

Leaks typically come from a clogged condensate drain line. Clear drain of debris and algae. If water continues to leak, make sure the AC is level. If it’s not, pour water into the lowest end until it drains properly.

What should I do if my AC smells musty or burning?

Musty odors are caused by mold in the ductwork or drain pan. Replace the filter and sanitize the drain pan. Burning smells could be electrical problems or a damaged motor. Shut the system down and call for service right away.

Call the Professionals 

There are plenty of problems you can troubleshoot on your own. Replacing a filter and clearing a drain line are no-brainers for most homeowners. Refrigerant leaks, compressor issues, and electrical problems are another story. These require a certified HVAC technician to safely make repairs.

Prevent AC breakdowns with annual maintenance. Change your filter every 1-3 months. Have a professional HVAC technician come out once a year to keep your system running smoothly. Avoid AC headaches by performing regular maintenance.