AC Not Keeping Up With Texas Heat? Common Reasons

Cooling is a balance. Heat enters the home through the roof, walls, windows, ducts, and air leaks, while the air conditioner removes heat and moisture. When removal falls below gain, indoor temperature drifts upward no matter how long the system runs.

That imbalance can come from the equipment side, the house side, or both. Understanding which side is contributing keeps homeowners from replacing a system that was never the main problem.

• Restricted airflow from a loaded filter or an undersized return
• A dirty evaporator coil that cannot absorb heat from return air
• A dirty outdoor condenser coil that cannot reject heat to 100-degree air
• A refrigerant charge that is low, which may indicate a leak
• A weak blower motor or a failing capacitor
• A compressor that is losing capacity as it ages
• A thermostat or sensor reading the wrong temperature

• Thin or displaced attic insulation above the ceiling
• Duct leakage and poor duct design in a very hot attic
• Air leakage around windows, doors, recessed lights, and attic hatches
• Heavy west-facing sun exposure through untreated glass
• Room additions or enclosed patios that were never added to the cooling load
• Inadequate return air, which starves the system even when supply ducts are fine

Homes that recover overnight but struggle by mid-afternoon often have a heat-gain or capacity issue. Homes that never recover, even at 3 a.m., more often have an equipment or refrigerant problem worth having inspected promptly.

1. 1Note the indoor temperature and thermostat setting at 8 a.m. and again at 5 p.m.
2. 2Feel the air at several supply vents — weak flow in some rooms points toward ducts.
3. 3Hold a hand near the return grille; very weak return suction points toward airflow restriction.
4. 4Check for ice or frost on the copper lines at the indoor unit.
5. 5Note whether the home recovers within a few hours after sunset.

• Temperature difference between return and supply air
• Static pressure and airflow across the coil
• Refrigerant pressures and superheat or subcooling values
• Electrical readings on the compressor, blower, and capacitors
• Condition of both coils and the condensate drain
• A visual review of accessible ductwork and insulation