Why is my AC running but not blowing? A Portland tech explains

If you’ve noticed that your AC is running but there is little to no air coming from your vents, there likely is an issue with your air conditioner. If you place your hand in front of any of your AC vents, you should be able to feel a decent amount of cool air coming from it.

If the airflow is weak, but you can hear your AC running, you’re likely dealing with one of the following issues:

  1. The vents are closed or obstructed

  2. There is an issue with your ducts

  3. You have a clogged filter

  4. Your AC has dirty coils (indoor or outdoor)

Below, we’ll walk you through each of these issues in more detail, so you can get a better idea of which issues you can fix yourself and which issues you’ll need to call a professional for.

If you’d prefer to have your issue handled directly by a professional, reach out to us. Portland homeowners rely on us to provide them with the best recommendations, prices and AC repair services.

Reason #1: Vents are closed or obstructed

We know it sounds obvious, but if your vents are closed or obstructed, the airflow will of course be reduced.

Many homeowners like to close or partially close some vents in certain rooms they don’t want as heated or cooled. It can be easy to forget to reopen these vents once the seasons change.

Your airflow can also be reduced if your vents or your register is covered or restricted.

The solution? Make sure all of your vents are fully opened and are completely uncovered by furniture or anything else that may be blocking them.

Note: Your vents could also be blocked on the inside with debris or other obstructions. We’ll get into this in more detail, next.

Reason #2: Duct design or damage

One of the most common reasons that your AC is running but not blowing a significant amount of cold air is because of issues with the ductwork.

Your ducts are responsible for distributing cool air throughout your home. If your ducts are blocked, have leaks or were poorly designed, they won’t be able to distribute air evenly, which is why you may notice reduced airflow.

Issue #1: Improper design

If your ducts were recently replaced or installed, the issue is most likely an issue with the design of the ductwork. If there are too many sharp turns in the ductwork, it can prevent air from being evenly distributed to each room. If you think the design of your ductwork may be the issue, reach out to the company that recently replaced or installed your ductwork. They should be able to assess the quality of work and replace any ductwork that was designed improperly.

Issue #2: Clog or obstruction

If your ducts were not recently replaced or installed, you’re likely dealing with a clog or leak. Over time, your ductwork can become clogged by debris or sometimes even small animals. This will prevent air from easily flowing through ducts, which is why you may notice reduced airflow, even if your AC is running properly.

Issue #3: Leaks or holes

Holes or leaks in your ductwork can significantly reduce airflow if they are large enough. If you’ve noticed that your AC has increased significantly and there is reduced airflow from your vents, you may have a leak. If you think you are dealing with a leak or clog, you’ll want to reach out to a professional for help. They will be able to safely assess the issue and suggest either cleaning your ducts or repairing them if there are leaks or holes.

Reason #3: Clogged filter

If your filter is clogged, your AC won’t be able to draw in as much unconditioned air, which in turn means it won’t be able to cool as much air. This may be why you’re noticing reduced airflow.

On average, your air filter needs to be replaced every 1-3 months. If it’s been a few months since you replaced your filter or your AC has been running frequently (like during the summer months), you’ll want to check your air filter and replace your filter if it’s dirty.

Reason #4: Dirty coils

Both your indoor and outdoor AC units have coils. In your indoor unit, unconditioned air is blown over the coils, and the heat from your air is absorbed via refrigerant, a substance flowing through the coils.

That heat is then moved to your outdoor unit where it’s released into the outdoor air via the coils in your outdoor unit.

If the coils in your indoor unit are dirty, it will be difficult for the refrigerant to absorb the heat from your indoor air.

If the coils in your outdoor air are dirty, it will be difficult for your AC to “offload” the heat from your indoor air into the air outside.

When your coils are dirty, your AC is not able to cool as much air, which is why you may notice reduced airflow or warmer air coming from your vents.

If you think either your indoor unit or outdoor unit has dirty coils, you’ll need to reach out to a professional for help. Your AC’s coils are very fragile, so you won’t want to attempt cleaning them on your own, as you could easily damage your system.

Still having issues with your AC? Reach out to Four Seasons!

If you’re still having issues with your AC’s airflow, reach out to us. We’ve been serving Portland homeowners since 1979, and the community relies on us to provide them with excellent AC repairs. No matter what the issue is, you can trust us to accurately diagnose the issue and expertly repair your system.

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