A/C Won’t Cool? 8 Things to Check Before You Call
It’s a hot, humid D.C.-area afternoon, the A/C is running, and the house just won’t cool down. Before you call for service, these eight checks solve many cooling problems — and the rest help us fix it faster.
1. Check the thermostat
Set it to Cool, a few degrees below the room temperature, and the fan to Auto. On “On,” the fan blows constantly — even when the air isn’t being cooled — which can feel like it’s not working. Replace the batteries if the screen is dim.
2. Replace the air filter
A clogged filter is the number-one cause of weak cooling. It chokes airflow and can freeze the indoor coil. If the filter is dirty, change it.
3. Check the breaker
An A/C has both an indoor and an outdoor component, sometimes on separate breakers. If the outdoor unit is silent, check for a tripped breaker.
4. Look for ice
If you see frost or ice on the refrigerant lines or indoor coil, the system is frozen. Turn it off and let it thaw fully — running it iced up can damage the compressor. A frozen unit points to low refrigerant or poor airflow.
5. Clear the outdoor unit
The outdoor condenser sheds heat, and it can’t do that if it’s smothered. Clear grass, leaves, and debris, and trim back plants so there’s a couple of feet of breathing room on all sides.
6. Check the condensate drain
A clogged drain line can trip a safety switch that shuts the system down. If there’s standing water near the indoor unit, that’s a clue.
7. Close up the house
On extreme days, open windows, blinds in direct sun, and heat-generating appliances all make it harder to keep up. Close things up and draw the shades on the sunny side.
8. Listen and feel
Is the outdoor fan spinning? Is the air from the vents actually cool, just weak — or room temperature? These details tell a technician a lot, so note them before you call.
If you’ve worked through the list and the house still won’t cool — or you found ice, standing water, or a dead outdoor unit — it’s time for a pro. Our NATE-certified team gets cooling back fast. Request A/C service.
See our air conditioning repair services, keeping homes cool across Washington, D.C. and Maryland for 40+ years.
A/C Cooling FAQs
Why is my A/C running but not cooling?
The usual suspects are a dirty filter, a frozen coil, low refrigerant, a tripped breaker, or a blocked outdoor unit. Start with the filter and the breaker, and look for ice.
Should I turn off my A/C if it’s frozen?
Yes. Shut it off and let it thaw completely before running it again — operating a frozen system can damage the compressor. Then have the cause (airflow or refrigerant) checked.
Why is warm air coming from my vents?
Check that the thermostat is on Cool and fan on Auto. If it still blows warm, it could be low refrigerant, a failed compressor, or an outdoor unit that isn’t running — that’s a service call.