Why Is My HVAC Not Cooling?


Typically split-system air conditioners have a lot of moving components, including an indoor air unit, outdoor unit, an air filter, a thermostat, and more. Any of these can have issues that contribute to your HVAC not cooling.

We all know how miserable it can be to suffer a hot night with an air conditioner that isn’t working. If you’re turning down the thermostat and still struggling to get the cooling you want in your home, any number of things could be causing it.

Typically split-system air conditioners have a lot of moving components, including an indoor air unit, outdoor unit, an air filter, a thermostat, and more. Any of these can have issues that contribute to your HVAC not cooling.

Learn more about the possible causes of your HVAC not cooling and how you can fix the problem.

Is Your Air Filter Dirty?

Air filters are a big part of the air conditioning system, even if they don’t seem like it. This component is designed to catch dirt and debris before it can end up in your house, degrading your indoor air quality, or inside of the system and affecting delicate components.

Image: Two Air Filters Side By Side, One Is Clean, The Other Is Dirty. Wondering Why Your Hvac Is Not Cooling? An Overfull Air Filter Could Be To Blame.
If you suspect that your air filter is dirty, it’s important to check. This is a potentially bigger problem than just cooling – a dirty air filter can damage internal components or force a full shutdown as your system safeguards itself. Turn off the system, locate the air filter, remove it, and clean it. If you prefer, contact an HVAC professional to do this for you or replace your air filter as needed.

Do You Have Incorrect Thermostat Settings?

The most common – and obvious – cause of air conditioners not blowing cool air is the wrong setting on the thermostat. If you have other people in your home adjusting your thermostat, it’s easy for it to be accidentally switched to heat or fan mode instead of cooling mode. You could also have people turning the thermostat up.

Check your thermostat to make sure it’s on cooling mode and set at a low temperature. Once the system is reset, wait a few minutes and check if there’s cool air coming out. Hopefully, that’s all it takes to get your air conditioning working properly.

Are the Condenser Coils Clogged?

Central air conditioning has an outdoor condenser unit and a large coil that lines the outside of it. This coil is designed to draw air through it and into the outdoor unit, drawing heat out of your home and bringing cool air in. The coil has many small metal fins that are tightly spaced, leaving areas where dust, dirt, and debris can get stuck.

If your air conditioner is running but not cooling, it could be because of a blocked condenser coil. With its location outside, any number of things can end up in the coil, such as dust, dirt, leaves, grass clippings, pine needles, and other organic material.

This can impact how well your air conditioner functions, but if it gets bad enough, it could shut your whole system down. Be sure to inspect the coil visually and clean it gently with a vacuum and brush attachment. If you think the blockage is severe, bring in a pro HVAC technician to clean it for you.

Is Your Refrigerant Leaking?

Refrigerant is the lifeblood of your air conditioner. Refrigerant flows through the indoor and outdoor coils, moving from a liquid state to a gaseous state to draw heat out of your home and outside, conditioning the air.

Image: An Hvac Tech Checking The Refrigerant Levels Of An Ac Unit.
Air conditioners need a precise amount of refrigerant to work as they should. If your refrigerant is leaking, your system can’t work properly and will run for longer periods without cooling.

A severe leak can end up shutting down your system to prevent damage. If you think there’s a leak in your refrigerant, contact a professional to fix it. Don’t simply replace the refrigerant!

Is Your Air Conditioner Too Small?

Air conditioners come in a range of sizes, but they’re not measured in small, medium, and large. They’re measured in BTUs, or British Thermal Units, like 10,000 or 12,000 BTUs. These essentially measure how well an air conditioner can cool your home, and it’s important to choose the right BTUs for your home’s square footage, insulation, and climate. If you’re not sure what size is best, consult with an HVAC professional.

If you have a unit that’s too large for your home, it will cycle on and off without working properly. If it’s too small, it will work harder and still not cool your home, all while driving up your energy bills. This also takes a toll on the system from stress.

The best solution is to replace your system with one that’s appropriately sized for your home. Though there’s an upfront cost, this is offset by better energy efficiency and better cooling in your home over time, not to mention a longer lifespan for the system itself.

Image: Two Condensers Side By Side, This Shows How Small Some Condensers Can Be. You'Ll Want To Fit The Hvac System To The Size Of Your Home.
Looking for air conditioning or HVAC installation, repairs, or maintenance? Contact Service Champions to schedule your appointment!