Why Is My AC Not Cooling? (San Antonio)
If your AC is running but blowing warm air, the cause is almost always one of six things: a clogged filter, a tripped breaker, wrong thermostat settings, a dirty outdoor unit, a frozen coil, or low refrigerant from a leak. The first four you can check yourself in about ten minutes. The last two need a licensed pro. Here is exactly what to check, in order, and when to stop and call for help.
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Call Ashley Now (830) 538-0713 Prefer to type? Get free quotes online in 45 secondsCheck these 6 things, in this order
- Thermostat settings. Make sure it is set to Cool, not Fan, and set 3 to 4 degrees below the current room temperature. Dead batteries cause more "broken AC" calls than most people would guess.
- Air filter. Pull it out and hold it up to a light. If you cannot see light through it, that is your airflow problem. In a San Antonio summer with the system running all day, filters clog in 30 to 60 days, not 90.
- Breaker panel. Find the breakers labeled AC, HVAC, or condenser and check whether one has tripped. Reset it once. If it trips again, stop. A breaker that keeps tripping means an electrical fault that needs a pro.
- The outdoor unit. Is the fan on top spinning? Is the coil caked with dust, grass clippings, or cottonwood fluff? Gently rinse the fins with a garden hose (system off first). A dirty condenser in 100° heat cannot dump heat, so the house stays warm.
- Ice on the lines or coil. Look at the copper lines at the outdoor unit and the indoor coil if you can reach it. Ice means restricted airflow or low refrigerant. Turn the system off, set the fan to On to speed thawing, and book a pro.
- Warm air the whole time. If you have done all of the above and the vents still blow warm, the likely causes are a refrigerant leak, a failed capacitor, or a failing compressor. All of these require a licensed technician with gauges and parts.
Why San Antonio ACs quit in summer
Our summers are a stress test. Weeks of 100°+ days mean systems run 12 or more hours straight, attic temperatures pass 130°, and weak parts fail at the worst time. Two local factors make it worse: San Antonio's hard water leaves scale on coils and condensate lines when systems are serviced with it, and the dust plus live oak pollen loads filters and condensers faster than national maintenance schedules assume. That is why an AC that limped through May dies in July, and why afternoon repair calls stack up city-wide during a heat wave. The companies with open slots go fast.
What a pro will actually do
A licensed tech will measure refrigerant pressures, test the capacitor and electrical components, inspect the coil, and give you a diagnosis with a price before any work starts. If the fix is major, get more than one opinion. Repair prices for the same job vary widely across San Antonio, which is exactly why we built a free service that makes up to three local pros quote your repair instead of you taking the first number you hear.
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Call Ashley Now (830) 538-0713 Or request free quotes online. Most homeowners hear back within 1 to 2 hours.Frequently asked questions
Why is my AC running but not cooling the house?
The most common causes are a clogged air filter, a refrigerant leak, a frozen evaporator coil, a failing capacitor, a tripped breaker, or a dirty outdoor condenser. Check the filter, thermostat settings, and breaker first. If air is still warm after those checks, the problem usually needs a licensed technician.
Should I turn my AC off if it is not cooling?
Yes, if the unit is running but not cooling, switch the thermostat to off and set the fan to on. Running a system with a frozen coil or failing compressor can turn a small repair into a major one. Letting a frozen coil thaw for a few hours also makes the technician's diagnosis faster.
Why does my AC freeze up in summer?
A coil usually freezes from restricted airflow (a dirty filter or blocked vents) or low refrigerant from a leak. Ice on the copper lines or indoor coil is a warning sign. Turn the system off, let it thaw, replace the filter, and have a pro check the refrigerant charge.
How fast can an AC technician come out in San Antonio?
Through HVAC Flow Solutions, most San Antonio homeowners hear from a local pro within one to two hours. Up to three vetted companies compete for your job, which usually means faster response than calling shops one at a time.
Wondering what the repair will run you? See our guide to AC repair costs in San Antonio, or learn how to choose the right contractor before you hire.
This guide is for general information and reflects HVAC practices in the San Antonio, Texas area. Last updated September 2026.