It is the middle of a Houston summer, your thermostat reads 82 degrees, and your AC is blowing warm air. Before you panic, there are several common issues you can check yourself that might save you a service call. Here are five things to look at first.
1. Check Your Air Filter
A clogged air filter is the number one cause of cooling problems we see in Houston homes. When the filter is packed with dust and debris, it restricts airflow to the point where your evaporator coil can freeze solid, and a frozen coil cannot cool your home.
Pull out the filter and inspect it. If it looks gray and matted, replace it immediately. After replacing a badly clogged filter, give your system a couple of hours to recover before judging whether the problem is solved.
2. Check Your Breaker Panel
HVAC systems typically use two breakers — one for the indoor air handler and one for the outdoor condensing unit. If only one trips, your fan may blow air that is never cooled. Head to your electrical panel and look for any breakers in the middle position. Flip them fully off, then back on.
If a breaker trips repeatedly, do not keep resetting it. That indicates an electrical issue that needs professional diagnosis.
3. Check the Attic Safety Switch
Many Houston homes have a secondary float switch or safety cutoff installed in the attic near the air handler. This switch shuts down your system if the drain pan fills with water, preventing ceiling damage from condensate overflow.
If your system suddenly stops working, check the attic. The drain line may be clogged with algae or debris, causing the safety switch to activate. You can sometimes clear a minor clog by pouring a cup of white vinegar down the drain line.
4. Check Your Thermostat
It sounds basic, but thermostat issues account for more service calls than you might think. Verify these settings:
- Mode is set to “Cool,” not “Heat” or “Fan Only”
- Temperature is set below the current room temperature
- Batteries are fresh if your thermostat uses them
- Schedule has not been accidentally changed
Try setting the temperature five degrees below room temperature and waiting a few minutes to see if the system kicks on.
5. Look for Oil Residue Around Your Outdoor Unit
Walk outside and inspect your condensing unit. If you see oily residue on the copper lines or around connection points, you may have a refrigerant leak. Refrigerant is the lifeblood of your cooling system, and even a small leak will degrade performance over time until the system cannot cool at all.
A refrigerant leak is not a DIY fix. This requires a licensed technician to locate the leak, repair it, and recharge the system with the correct amount of refrigerant.
When to Call a Professional
If you have checked all five of these items and your system still is not cooling properly, it is time to call in the experts. Issues like compressor failure, bad capacitors, or electrical faults require professional tools and training to diagnose safely.
Contact HTM for fast, reliable AC repair across the Houston metro area. We offer same-day service when available and never charge overtime rates.