Short answer

When your AC is running but not cooling, it usually means the system is operating but something is preventing it from removing heat properly. In many cases, the issue is related to airflow or maintenance, but there are situations where professional service is needed.

The key is understanding what the system is doing and what signs matter.

What homeowners usually notice first

Most homeowners notice the problem when they come home to a hot house. Others notice that air is coming out of the vents, but it does not feel as cold as they are used to.

In some cases, homeowners may notice little to no airflow at all. These symptoms all point to a system that is trying to run but cannot cool effectively.

The most common causes we see in the field

The most common reason an AC is not cooling is a dirty air filter.

A dirty filter restricts airflow, which starves the system of the air it needs to operate correctly. When airflow is restricted, cooling performance drops quickly.

The second most common issue is lack of maintenance. Air conditioning systems rely on clean evaporator and condenser coils. When these coils are dirty, the system again becomes starved for airflow and heat transfer, which severely reduces cooling capacity.

In older systems, another major cause is a refrigerant leak. When refrigerant levels drop, the system can no longer absorb and move heat effectively, resulting in poor or no cooling.

A cause that looks scary but is sometimes fixable

Ice buildup on the refrigerant lines or indoor coil often worries homeowners.

Sometimes ice does indicate a more serious issue, but other times it is caused by something simple, like a dirty filter or restricted airflow. The important thing to understand is that ice buildup is a symptom, not the root cause.

When this is a real red flag

There are certain signs that mean your AC should be looked at sooner rather than later.

If the AC breaker is tripping, if you notice any burning smells, or if you hear loud or unusual noises, the system should be shut off and evaluated. Ice buildup is also a red flag. Ice does not resolve itself, it only gets worse over time.

Ice buildup also prevents proper diagnostics. If a system is frozen, it cannot be accurately evaluated until it has fully thawed.

What homeowners can safely check themselves

The first thing to check is the air filter. If the filter is dirty, replace it.

If there is ice buildup, turn the system off and allow it to fully defrost before trying to run it again. Simply changing the filter will not fix the issue if ice has already formed, because the ice itself continues to restrict airflow.

Once the system is completely thawed, you can attempt to restart it. If the issue returns, it’s time to call a professional.

What homeowners should not do

Homeowners should not allow the AC to run continuously when it is not cooling. This can cause additional damage and turn a manageable repair into a more serious problem.

It’s also important not to reset breakers repeatedly or attempt to add refrigerant yourself. When cooling issues persist, the safest option is to shut the system off and call a trained technician.

How Bigfoot handles AC not cooling calls

At Bigfoot, our goal is to find the source of the problem, not just apply a quick fix.

When you call, you speak with a real HVAC technician who will ask questions to help determine what’s happening. If the system appears to be frozen, we may delay dispatch until the unit has fully defrosted. Sending a technician to a frozen system only slows the process.

We are a repair-first company, and our vans are stocked with many universal parts so we are prepared to complete same-day repairs whenever possible and get your cooling restored as quickly as we can.