Why Your AC Runs Constantly in Houston Summers

If your air conditioner seems to run from early morning until late at night without ever cycling off, you might assume something is broken. Sometimes it is. But in Houston, constant running is also a function of the environment. Understanding the difference helps you know when to call a technician and when to make some adjustments around the house.

Houston's Climate Is Hard on AC Systems

Houston routinely sees heat indexes above 105 degrees in July and August. The humidity makes it worse, because humid air holds heat more stubbornly than dry air. When it's that hot outside, a properly functioning AC system may still need to run for long stretches just to maintain 75 degrees inside. That's not a malfunction, that's physics.

Where things get concerning is when your system runs constantly but can't keep up, or when your energy bills spike far beyond what you'd expect for the conditions.

Common Causes of Constant Running

• Dirty air filter restricting airflow (the most common and easiest fix)
• Low refrigerant, which reduces the system's ability to transfer heat
• Dirty evaporator or condenser coils reducing efficiency
• Duct leaks letting cooled air escape into the attic before it reaches your rooms
• A system that was sized too small for the home
• Thermostat set lower than the system can realistically achieve on peak-heat days
• Poor attic insulation letting heat radiate down into living spaces

What You Can Check Yourself

Start with the basics. Check your air filter and replace it if it's dirty, a clogged filter is the single most common reason for a struggling system. Make sure all your supply and return vents are open and unobstructed. Check that the outdoor condenser unit isn't buried in shrubs or blocked by debris. And confirm your thermostat is working correctly by comparing its reading to a separate thermometer.

When to Call a Pro

If you've checked the filter and cleared any obstructions and the system still can't keep up, it's time to call an HVAC technician. Signs that warrant a call right away include ice forming on the refrigerant lines, warm air blowing from the vents, unusual sounds from the outdoor unit, or a sudden jump in your electric bill with no change in habits.

A technician will check refrigerant levels, inspect the coils, test the capacitor and contactor, and measure airflow. Most problems that cause constant running are straightforward to diagnose and fix, but they won't fix themselves over a Houston summer.