Why Is My AC Running But Not Cooling?

by | Jun 1, 2022 | AC Maintenance, AC Repair, Air Conditioner, Air Conditioning Maintenance, All, Articles

In our hot and humid Wisconsin summers, air conditioning is a necessity. You become particularly aware of that when your air conditioning isn’t working properly. And when your AC is actually running but not cooling your house, it’s more than uncomfortable. It’s expensive. Unless you enjoy paying for nothing, you’ll be highly motivated to figure out why your air conditioning is running but not doing its job. In this post, we’ll explore some of the most common reasons and what you can do about them.

Air Conditioning Components

Before we delve into possible problems and solutions, it’s important to know a little about how your air conditioning system works. You probably know that an outdoor unit sits somewhere outside your house; that’s the condenser unit (either AC or heat pump). But there’s a lot more to it. Split-system air conditioners have a lot of moving parts, including an indoor air handler unit (furnace or fan coil), an evaporator coil, air filter, thermostat and copper tubing (refrigerant lines) that connect the indoor and outdoor units. When your AC isn’t cooling the house, something could be amiss in any of these places.


The easiest item to check is your thermostat. If you notice your home is simply not cooling, especially if there are zones in your home, look at thermostat settings. Be sure it is set to cool. That sounds obvious, but most systems have a separate fan setting and it might be that your fan is running, but the system is not set to cool. It could be that the AC is off, or even set to “heat” rather than “cool.” If that’s the case, just switch it to “cool” and wait a few minutes; if cold air starts blowing, then the problem is solved!

Air Filter

Another factor that can cause your Air Conditioning to struggle to cool your home is a dirty air filter. There’s probably an air filter located in or around the indoor air handler unit. The filter catches dirt, dust and other airborne particles as they enter the air handler unit. It keeps the components inside the system cleaner and operating more efficiently and can help keep the air in your home cleaner as well. A dirty air filter can block airflow and reduce cooling to your home. In extreme cases, it can cause the system to shut down completely. You can deal with this issue yourself. Find your system’s air filter. Be sure to turn the system off completely before doing anything else. Then, remove the filter. If it’s dirty, simply clean it. Cleaning methods differ depending on the system. Typically, you can vacuum the dust and dirt off with the bristle attachment of your vacuum cleaner; then if your air filter is designed to get wet, soak it in a 50/50 mix of water and white vinegar. Let it dry completely and reinstall (being careful to put it back in the same way).

Outdoor Unit

The exterior of the condenser unit features a large outdoor coil, which wraps most of the way around the outside of the unit. The coil includes a series of thin metal “fins” which are spaced very tightly together. If your air conditioner is running, but not lowering temperatures inside, one issue could be a blocked or clogged condenser coil. When operating correctly, the condenser fan draws air into the outdoor unit through the condenser coil to pull heat energy out of your home. Dirt, grass and other airborne debris can accumulate between the fins, clogging the coil. A dirty coil can lead to reduced energy efficiency, lack of cool air from the registers, or in extreme cases, complete system shutdown or damage to the compressor from overuse. All of this means that your outdoor unit should have clearance all around it. No bushes or other debris should touch your AC. You can clean the coil by carefully vacuuming it with the brush attachment of your vacuum or rinsing it gently with a hose.

Other Issues

All of the above are issues that you can deal with yourself. If you have done all of these and your AC is still not cooling your home, it’s time to call the experts at Quality Heating. It could be that you have a damaged heat pump, or that the evaporator coil is frozen, or even that you have a refrigerant leak. Finally, it might just be that your air conditioning system is not designed to adequately cool your home. You wouldn’t think that would be the case, but here at Quality Heating, we’ve seen it. Whatever the problem, we can diagnose it and fix it.


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