There’s nothing more frustrating than turning on the air conditioner during a hot San Antonio summer only to feel warm air coming from the vents. If you’ve been asking, “Why is my AC blowing warm air?” you’re definitely not alone. Many homeowners in the area deal with their AC not cooling each year, and knowing what to check first can help you avoid unnecessary stress, discomfort, and repair costs.
Below are common reasons your AC is not cooling properly, along with guidance on when to call for professional HVAC service in San Antonio.
Frozen Evaporator Coil 
A frozen evaporator coil is one of the top reasons an air conditioner stops cooling efficiently. Ice build-up prevents the coil from absorbing heat from the air inside your home. When that happens, the system keeps running but the air coming from your vents stays warm or barely cool.
This issue is often caused by airflow restrictions or low refrigerant levels. If your AC runs continuously with little to no cooling or if you notice ice on the indoor unit, turn it off and contact a professional to assess the system.
Dirty Air Filter
A clogged air filter can restrict airflow, which reduces your system’s ability to cool your home. In some cases, it can even lead to frozen coils, forcing the system to work harder and potentially shortening its lifespan.
Replacing or cleaning your filter every one to three months is a simple and effective way to improve efficiency and prevent problems. It’s a key part of regular air conditioning maintenance for San Antonio homeowners.
Low Refrigerant
Refrigerant is the substance your AC uses to remove heat from the air inside your home. If the system is low on refrigerant, it won’t cool properly. This issue typically indicates a leak, which must be diagnosed and repaired by a licensed HVAC technician.
If your system is struggling to cool despite running constantly, it may need a refrigerant recharge and leak inspection. This is not a DIY fix and should be handled by a professional AC repair team.
Faulty Thermostat 
Sometimes the thermostat is to blame rather than the AC unit itself. If the thermostat is malfunctioning or not reading temperatures accurately, your AC may not receive the signal to turn on or may shut off too soon.
Check to make sure your thermostat is set to “cool,” the temperature is set correctly, and that it has working batteries if applicable. If these steps don’t help, a technician can test and replace the thermostat as part of a routine HVAC service.
Failing Capacitor
The capacitor is responsible for starting the AC unit and keeping it running. When it begins to fail, the system may have trouble turning on or may shut off unexpectedly. A failing capacitor can keep your AC from cooling effectively.
Because capacitors store an electrical charge, they should only be replaced by a qualified technician. If your system is not responding or is starting and stopping unexpectedly, it could be time for a service call.
AC Unit Too Small for the Space
If your air conditioner is not the right size for your home, it may never cool effectively. An undersized unit will run continuously without reaching the desired temperature, leading to high energy bills and premature wear.
This issue is more common in homes that have been expanded or remodeled. If you’ve always noticed your AC struggles on hot days, it’s worth having your system evaluated. An HVAC expert can determine if the unit is appropriately sized for your home and recommend the right replacement if needed.
When to Call for AC Repair Services in San Antonio 
While some AC issues can be solved with basic maintenance, others require professional expertise. If your AC is blowing warm air, not turning on, or simply not keeping up with the heat, it’s time to call for AC repair in San Antonio.
Shafer Services Plus is a trusted local provider for fast and effective air conditioning repair in San Antonio, TX. Our certified technicians can quickly diagnose and repair issues to restore comfort to your home. Whether it’s a faulty capacitor, low refrigerant, or a frozen coil, we have the tools and experience to get the job done right.
Prevent Cooling Problems with Regular Maintenance
Preventive care is the best way to avoid unexpected breakdowns and keep your system running smoothly. Routine air conditioning maintenance includes:
- Cleaning coils and components
- Replacing air filters
- Checking refrigerant levels
- Inspecting the system for signs of wear or damage
Shafer Services has some of the best HVAC technicians in San Antonio to help your system operate at peak efficiency, saving you money on energy bills and extending the life of your equipment.
Final Thoughts
If your AC is not cooling properly, don’t wait until the problem gets worse. From clogged filters to more serious mechanical issues, there are several reasons your system may be underperforming. When in doubt, schedule a professional inspection with a trusted provider.
Shafer Services Plus is proud to serve San Antonio homeowners with top-rated AC repair and HVAC service. Whether you’re searching for “AC repair near me” or need emergency assistance, our team is ready to help you stay cool all summer long.
Need Air Conditioning Repair in San Antonio, TX?
Contact Shafer Services Plus today to schedule a service call and get your system back to peak performance.