Top Causes of AC System Blowing Hot Air

Is Your AC system blowing hot air? We get this call a LOT in San Antonio and Austin Texas. There are several components that could be malfunctioning. Our friendly AC technicians have the tools and the expertise to fix it while giving you affordable options! Here are the top causes and the associated components:

1. Low Refrigerant Levels
   • Component: Refrigerant lines, evaporator coil, or compressor.
   • Leaks or improper charging can reduce refrigerant, preventing the system from cooling air effectively.
2. Thermostat Issues
   • Component: Thermostat.
   • A miscalibrated, incorrectly set, or malfunctioning thermostat may signal the system to heat instead of cool or fail to activate the cooling cycle.
3. Dirty or Clogged Air Filter
   • Component: Air filter.
   • A blocked filter restricts airflow, causing the evaporator coil to freeze or the system to overheat, leading to warm air output.
4. Frozen Evaporator Coil
   • Component: Evaporator coil.
   • Poor airflow (from a dirty filter or blocked vents) or low refrigerant can cause the coil to freeze, halting the cooling process. Low refrigerant can also be the culprit.
5. Condenser Unit Problems
   • Component: Condenser coil, condenser fan, or capacitor.
   • Dirt, debris, or a faulty fan in the outdoor condenser unit can prevent heat dissipation, causing the system to blow warm air. If your condenser coil is so dirty that it’s clogged, that can cause your AC to blow hot air.
6. Compressor Failure
   • Component: Compressor.
   • The compressor circulates refrigerant; if it fails or overheats, the system can’t cool air, resulting in hot air output.
7. Electrical Issues
   • Component: Capacitors, relays, or wiring.
   • Faulty electrical components can prevent the compressor or fans from running, disrupting the cooling cycle.
8. Blocked or Leaking Ductwork
   • Component: Ducts.
   • Leaks, tears or obstructions in the ductwork can allow warm air from the attic or outside to mix with or replace cooled air. If you had work done on your roof recently, it’s possible some of your air ducts got smashed or torn. Also, pests such as roof rats or other wildlife can get into attics. They often seek cool air and water in your attic and can chew through your AC ducts and drain pipes causing your AC system to blow hot air.

In San Antonio and Austin’s hot climate, issues like dirty filters and condenser coils are common due to dust and pollen, while refrigerant leaks are frequent in older systems. Regular maintenance like AC tune-ups can help prevent many of these problems. If the issue persists, a professional HVAC technician should diagnose the system.

We are a local, family owned company who supports local communities all year long – our teachers, our veterans, our students, our parents, first responders, families in need. We aren’t like corporate-owned companies that are there to get a sale. We are part of YOUR local community and want to make sure our services are affordable as possible! 

Air & Plumbing Today offers NO trip charge, NO diagnostic fee and FREE estimates 7-days a week. If your AC system fails you on a weekend or at night, we’ll come out there and find out what’s wrong without charging you a dime if you’re a residential customer. Read our reviews and either call us or book online. Our friendly AC techs will greet you with a smile and they’ll find you an affordable solution.  Thank you for considering us!

San Antonio: 210-519-5959
Austin: 512-859-5959