AC Not Cooling? Troubleshooting Common Air Conditioning Problems

When it gets hot, the last thing anyone wants is for the AC to go on the fritz. A non-functional air conditioner can quickly turn your home from a comfortable sanctum into an oven. However, just because your AC isn’t cooling properly isn’t necessarily a sign it needs repairs (or replacement for that matter). In many cases, the issue can be traced to one or more common problems that can either be resolved on your own or with professional help. Here’s a guide to troubleshooting the most frequent reasons your air conditioning system might not be doing its job.

1. Thermostat Settings

Before diving into complex diagnostics, it’s usually best to start with the basics. These may sound like obvious measures, but checking for the most obvious causes for problems can save you plenty of time and money. Check the thermostat settings to ensure they haven’t been accidentally changed. Make sure the unit is set to “cool” and not just “fan” mode. Also, confirm the temperature is set lower than the current room temperature. If the thermostat is battery-powered, try replacing the batteries. In some cases, your problem may come down to a faulty or misconfigured thermostat preventing the air conditioner from activating properly.

2. Clogged or Dirty Air Filters

Part of good maintenance is making sure your air conditioner’s air filters get the maintenance they need. When filters are clogged with dust, pet hair, and other debris, airflow becomes restricted, and the system struggles to circulate cool air (all of which lowers efficiency and adds to your energy bills). Given that energy bills can add up (in 2019 alone, Canadians paid nearly $30 billion on energy bills), anything that contributes to keeping the bills low helps. This strain can also cause the evaporator coils to freeze, further inhibiting cooling performance. It’s a good practice to check and clean or replace air filters every one to three months (depending on usage and household conditions).

3. Blocked Condenser Unit

The outdoor condenser unit plays a vital role in releasing heat from your home. If the condenser is obstructed by dirt, leaves, or other debris, it can’t operate efficiently. Inspect the unit and gently clean the fins using a garden hose if you find they’ve gotten dirty. Ensure there is at least 60 centimeters of clearance around the unit for optimal airflow. Avoid using high-pressure water or attempt to clean internal components; these measures can damage the condenser unit and add to any problems you’re already experiencing.

4. Low Refrigerant Levels

Refrigerant is essential for your AC system to cool air effectively. If your unit is low on refrigerant, there may be a leak somewhere in the system. Signs of low refrigerant to clue you in to a problem include longer cooling cycles, ice on the refrigerant lines, or a noticeable hissing sound near the unit. As an early word of warning, topping up refrigerant isn’t a DIY task; a licensed HVAC technician will need to locate and repair the leak before recharging the system.

5. Frozen Evaporator Coils

Evaporator coils absorb heat from the air, but if they freeze over, the system cannot perform this function. Frozen coils are often caused by poor airflow due to dirty filters, blocked vents, or low refrigerant. If you suspect frozen coils, turn off the AC and allow the unit to thaw completely. Once defrosted, address the underlying cause to prevent future freezing.

6. Electrical or Mechanical Issues

Air conditioners rely on multiple components working together (such as fans, capacitors, and compressors). If any of these parts fail, the cooling performance may suffer or stop entirely. Unusual noises (like grinding or buzzing) may indicate a mechanical issue. Similarly, if the AC doesn’t turn on at all, it could be due to a tripped breaker or blown fuse. Check your electrical panel first before calling for repairs.

7. Ductwork Problems

Even if your AC is functioning properly, damaged or poorly sealed ductwork can prevent cool air from reaching your living spaces. Any leaks in the ducts can also lead to energy loss and uneven cooling throughout your home. Inspect visible ductwork for holes or disconnected sections, and consult a professional to conduct a pressure test or seal hard-to-reach areas.

8. Incorrect Unit Size

If your air conditioner is too small for the size of your home, it will struggle to keep up with cooling demands. Conversely, an oversized unit may cool the air too quickly without properly dehumidifying it, leading to discomfort. Given that AC prices are likely to rise in the future (to comply with new regulations), it’s a good idea to ensure you get the right-sized AC to avoid any unexpected costs. If you suspect your system is not appropriately sized, a certified HVAC technician can assess your home’s cooling needs and recommend the right solution.

A non-cooling air conditioner doesn’t always mean a major repair is needed. Many common issues have simple fixes or can be prevented with routine maintenance. However, when in doubt, it's always best to consult a qualified professional to avoid causing further damage and to ensure you get the issue resolved efficiently. Regular servicing and attentive care go a long way toward keeping your air conditioning system running smoothly all day long.

When you need a reliable technician to take a look at your HVAC system, give JLN HVACS Solutions Inc. a call. We have a wealth of experience with a wide range of HVAC-related issues, from malfunctioning air conditioners to issues with the furnace. Whatever your problem, you can count on us to take care of it for you and make your home comfortable again with a minimum of fuss. Give us a call now at (647) 696-8915 the next time you need your HVAC system looked at.