AC Not Turning On? 8 Things to Check Before You Call (San Antonio Guide)

Few things are worse than walking past the thermostat on a 100° day and realizing the house is getting warmer. Before you call anyone, run through these checks, a few of them take less than five minutes.

1. Check the Thermostat

Make sure it's set to Cool, the temperature is set below the current room temperature, and the screen isn't blank. A blank screen usually means dead batteries, replace them and try again.

2. Check the Breaker

Look at your electrical panel for a tripped breaker labeled AC, condenser, or furnace/air handler. Reset it once. If it trips again, stop, a breaker that keeps tripping is a sign of an electrical problem or a failing part, and it needs a technician.

3. Check the Outdoor Disconnect

Next to your outdoor unit there's a small box with a shutoff switch or pull-out block. Make sure it's on and fully seated. Sometimes it gets bumped by landscapers or kids.

4. Check the Furnace / Air Handler Door

Indoor units have a safety switch that shuts everything off if the panel door isn't closed tight. If someone recently changed the filter, make sure the door is snapped back in place.

5. Look for a Full Drain Pan or Tripped Float Switch

Many systems have a float switch that shuts the AC off if the condensate drain backs up, a very common problem in humid San Antonio summers. If you see water in the pan by your indoor unit, the drain line is likely clogged. See our guide to AC leaking water.

6. Replace a Dirty Filter

A badly clogged filter can cause the system to overheat or freeze up and shut down. Swap it out (here's how often to change your filter).

7. Listen to the Outdoor Unit

If the indoor fan runs but the outdoor unit is silent, or you hear a humming or buzzing but the fan doesn't spin, the problem is often a failed capacitor or contactor. These are common repairs, but they involve high voltage, so leave them to a pro. More in AC humming or buzzing.

8. Wait Five Minutes After a Power Outage

After a power flicker, many systems have a built-in delay before restarting. Give it a few minutes before assuming something is broken.

When to Call Right Away

Call a technician if a breaker keeps tripping, you smell burning, you see scorch marks, or the outdoor unit hums without the fan turning. If your system is older and this keeps happening, it may be time to look at a free replacement estimate.