AC Running But Not Cooling? 5 Things to Check Before You Call

September 29, 2026•2 min read

Your AC is on. You can hear it running. But the air coming out feels warm, or just not cold enough. In a Birmingham summer, that is a rough day.

Before you call anyone, there are a few easy things you can check. Some take two minutes. Some will tell you the problem is bigger than a quick fix.

1. Check the thermostat

Make sure it is set to COOL, not FAN or HEAT. Set the temperature a few degrees below the room temperature. If the screen is blank, try new batteries.

2. Look at the air filter

A clogged filter blocks air. Less air means weak cooling. Pull the filter out and hold it up to a light. If you can't see light through it, put in a new one.

3. Check the outdoor unit

Go outside and look at the big box with the fan on top. Is it running? Is it packed with leaves, grass, or dirt? Clear a few feet of space around it.

Turn the power off at the breaker before you clean anything on the unit. Never stick your hand inside it.

4. Look for ice

Ice on the copper line or on the indoor unit is a warning sign. It can mean weak airflow or a problem with the refrigerant. Turn the AC off and let the ice melt. Running the system while it is iced up can cause damage.

5. Check the breaker

A tripped breaker can shut off the outdoor unit while the indoor fan keeps blowing. Flip it back on one time. If it trips again, stop. Something is wrong, and it is not safe to keep trying.

When it is time to call

If you checked all five and the air is still warm, the problem is likely inside the system. It could be low refrigerant, a bad part, or a dirty coil. Those jobs need special tools and training. Adding refrigerant is not a DIY job.

That is where we come in. En Route Heating and Air works on homes and businesses in Birmingham, Hoover, Vestavia Hills, Homewood, Mountain Brook, Trussville, Bessemer, Chelsea, Pelham, and Alabaster.

Call us at 205-922-7170 and tell us what you found. It helps us get to the problem faster.

On the way. On time. Or we take $50 off.

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En Route Heating and Air

Heating and cooling help from the En Route crew in Birmingham, Alabama.

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