HVAC Airflow Problems: Things You Should Know

Over time, HVAC airflow problems can develop in your air conditioner due to the lack of periodic maintenance and timely tune-ups. With proper maintenance of your air conditioning unit, you can enjoy superior and uninterrupted AC performance throughout the summer season. Read further about common HVAC airflow problems and solutions.

Symptoms of Weak HVAC Airflow problems can be identified through the following symptoms:

  • Air conditioner blowing warm air
  • Your space having hot and cold spots
  • Low airflow or no air coming out from vents
  • Pressure imbalance causing doors to slam by themselves and strange whistling sounds.

Causes of HVAC Airflow Problems

Here are some significant reasons why your air conditioner is causing airflow problems and which airflow troubleshooting steps to consider:

1. Dirty Coils

Coils will retain the heat if they become dirty or clogged with the outside dust and debris. Your air conditioner has to perform overtime to cool your space if it has dirty coils. This can eventually result in airflow problems. Get your coils cleaned annually to prevent airflow problems. 

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Comment by Franco Oyuela on June 24, 2019 at 2:27pm

Causes of HVAC Airflow Problems.

Here’s a common HVAC airflow problem and one you can fix yourself!

Air-cooled air conditioning systems have what’s called a condensing unit, typically located outside or in a mechanical room. Outdoor units especially can become obstructed due to leaves and debris that have accumulated around the unit. Even systems in mechanical rooms can be obstructed by other equipment or storage items. Your system can overheat when there’s not enough airflow to the air conditioning unit.

Your first step to improve HVAC airflow should be to clear the area around your condensing unit.

One bit of advice we can offer for how to increase air flow through vents is to make sure all vents and registers are open and not blocked by furniture.

This issue is quite common in an office setting, especially when people don’t agree on the thermostat setting! You’ve seen it: a filing cabinet gets moved in front of the AC register because someone is too cold. The next thing you know, your HVAC airflow has been compromised.

When was the last time you changed your air conditioner’s filter?

That filter has an important job: to remove dust and debris from the air and keep it out of your equipment and your ducts. If the filter gets overloaded and clogged, it impedes your HVAC airflow, leading to those hot & cold spots and stuffy air. Debris in the equipment can damage parts as well.

Be sure to change your AC filter according to the manufacturer’s instructions and your system usage. That could mean as frequently as once a month.

What happens to all the dust that gets past your clogged AC filters? It winds up accumulating in the ductwork.


Sometimes, something as simple as a faulty thermostat, or even a low battery can be the cause of HVAC airflow problems.

Your HVAC system has blower fans that move the air through your ducts and throughout your space. If a blower motor is sluggish, that can impede HVAC airflow and cause the symptoms mentioned earlier.

In some cases (especially in a restaurant) the fan itself can become coated with grime which slows the operation and reduces airflow. Luckily it’s a simple matter to clean the fan.

Your air conditioner’s condenser coil is another part with an important job to do: release the heat that’s removed from your space.

Since it’s part of the outdoor unit and exposed to the elements, the coil can get so dirty that it can’t release heat. Then your unit has to work harder (and hotter) trying to cool your space. The result can be those HVAC airflow issues. That’s one reason you should not neglect having your coils cleaned regularly (usually once or twice a year).

This is a more common problem than you might imagine. Years ago, the thinking was “bigger is better” when it comes to HVAC sizing. Today we know that units with a capacity too large for the space run inefficiently, cycling on and off too frequently. That means they never run long enough to remove humidity from the space, making it feel stuffy and uncomfortable.

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