--- title: "AC not cooling in New Braunfels? Fix-it guide" description: "A homeowner-safe checklist for an AC that runs but won't cool — thermostat, filter, breaker, outdoor unit, frozen coil — and when to call a pro." canonical: https://newbraunfelsacguide.com/ac-not-cooling/ source: https://newbraunfelsacguide.com/ac-not-cooling/ --- 1. [Home](https://newbraunfelsacguide.com/) 2. AC not cooling Troubleshooting # Your AC is running but not cooling — here's what to check Before you call anyone, five quick checks fix most "blowing warm air" problems in a New Braunfels summer. Work through them in order. If the system still won't cool after the last one, that's your signal it needs a licensed pro, and [we'll connect you with one](/get-help/). ## AC strain in New Braunfels right now Checking today’s heat index… As of — Refreshes Hourly from station observations Authority [NOAA / NWS](https://www.weather.gov/) Start here ## What can I check myself when the AC isn't cooling? Run these five checks in order — each is safe to do yourself and resolves the most common causes. Turn the system off before pulling the filter or inspecting the coil The indoor coil that absorbs heat from your air. If it freezes over, the AC stops cooling. [Full definition](/glossary/#evaporator-coil) . 1. 1 Thermostat set to cool 2. 2 Air filter clean 3. 3 Breaker + disconnect on 4. 4 Outdoor unit clear 5. 5 No frozen coil **Cooling again?** You're set — no pro needed. **Still blowing warm?** Stop. The likely cause is refrigerant or the compressor — call a licensed pro. Homeowner-safe checks (with the how and why) - **Thermostat** — set to _cool_ and the target a few degrees below the room temperature. Confirm no one switched it to _fan_ or _heat_. - **Air filter** — turn the system off, pull the filter, and check it. A clogged filter is the most common cause of weak cooling; replace it if it is dirty. - **Breaker and disconnect** — check your electrical panel for a tripped breaker and the outdoor disconnect switch; reset if needed. - **Outdoor unit** — clear tall grass, leaves, and debris away from the condenser so it can shed heat. - **Frozen coil** — if you see ice on the indoor coil or refrigerant line, switch cooling _off_ and the fan _on_ to thaw it (1–4 hours). ![Heavily dust-clogged air conditioning filters, the most common cause of weak cooling](/_astro/dirty-filter.LVsXd6Bb_Z21ez4R.webp "Heavily dust-clogged air conditioning filters, the most common cause of weak cooling") A clogged filter like this is the single most common cause of an AC that runs but won't cool. Replacing it is a five-minute fix. Photo: Gerardolagunes / Wikimedia Commons — [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/) ( [source](https://commons.wikimedia.org/wiki/File:Dirty_AC_filters_2023_\(1\)_03.jpg) ) Don't damage the compressor ## What is the 3-minute rule for restarting an AC? Give the system a few minutes between power-off and restart, waiting at least 3 to 5 minutes. The compressor The outdoor unit that releases heat pulled from inside your home. [Full definition](/glossary/#condenser) needs time to equalize internal pressure; flipping it back on immediately can trip the breaker or, over time, shorten its life. Carrier advises leaving the power off about five minutes to let the system reset. [Carrier](https://www.carrier.com/us/en/residential/hvac-resources/air-conditioners/ac-not-blowing-cold-air/) ![A residential outdoor air conditioning condenser unit beside a house, showing the finned coil that sheds heat.](/_astro/condenser-outdoor.BrtBzYW8_Z1kv0JY.webp "A residential outdoor air conditioning condenser unit beside a house, showing the finned coil that sheds heat.") The outdoor condenser sheds your home's heat through these fins. Keep tall grass, leaves, and debris clear of it — a blocked unit can't cool, and it's the easiest outdoor check to do yourself. [Trane](https://www.trane.com/residential/en/resources/troubleshooting/air-conditioners/) Photo: Shixart1985 — [CC BY 2.0](https://creativecommons.org/licenses/by/2.0/) ( [source](https://commons.wikimedia.org/wiki/File:Outdoor_air_conditioner_unit_installed_in_residential_garden_space.jpg) ) When DIY stops ## When should I call a licensed HVAC technician? If the five checks above are clear and the system still blows warm, or the coil refreezes after thawing, stop. The remaining causes are low refrigerant The refrigerant in most pre-2025 systems. Manufacturing of new R-410A systems was banned in 2025, so parts will get scarcer. [Full definition](/glossary/#r410a) or a failing compressor, and by federal law only an EPA Section 608-certified A federal certification any technician must hold to legally handle refrigerant. Required by law, not optional. [Full definition](/glossary/#epa-608) technician may handle refrigerant. [U.S. EPA](https://www.epa.gov/section608/section-608-technician-certification-requirements) Running the system in this state risks the compressor, the single most expensive component to replace. Don't keep running an AC that's iced over or blowing warm. Turn it off and get a licensed New Braunfels technician to diagnose it before a small fix becomes a compressor replacement. Common questions ## AC not cooling — FAQs Why is my AC running but not cooling the house? The most common causes are a wrong thermostat setting, a clogged air filter, a tripped breaker, a debris-blocked outdoor unit, or a frozen indoor coil — all worth checking yourself first. If those are clear and it still blows warm, the likely culprits are low refrigerant or a failing compressor, which require a licensed technician. [Source: Carrier](https://www.carrier.com/us/en/residential/hvac-resources/air-conditioners/ac-not-blowing-cold-air/). Should I turn my AC off if it is not cooling? Yes — if it is blowing warm air or you see ice on the coil or lines, turn the cooling off. Running a frozen or low-refrigerant system can damage the compressor, the most expensive part to replace. Switch the fan to _on_ to help a frozen coil thaw. [Source: Carrier](https://www.carrier.com/us/en/residential/hvac-resources/air-conditioners/will-frozen-ac-fix-itself/). How long does a frozen AC coil take to thaw? Usually 1 to 4 hours with the cooling off and the fan running, depending on how much ice built up. If the coil freezes again after thawing, that signals restricted airflow, low refrigerant, or a mechanical fault — stop and call a licensed technician rather than repeating the thaw. [Source: Carrier](https://www.carrier.com/us/en/residential/hvac-resources/air-conditioners/will-frozen-ac-fix-itself/).