Why Your AC Is Running But Not Cooling Your House
If your AC is running but not cooling, the most common causes are a dirty air filter, a frozen evaporator coil, low refrigerant, a failed capacitor, or a problem with the outdoor condenser unit. Some of these you can check safely in a few minutes, while others require a technician to prevent major damage.
Quick Checks You Can Do Right Now
Set thermostat to COOL and lower temperature 3–5°
Replace or inspect the air filter
Check the breaker and outdoor disconnect
Look for ice on copper refrigerant lines
Confirm the outdoor fan is spinning
Make sure supply vents are open and not blocked
When You Should Call an HVAC Technician
Ice keeps forming on the system
Outdoor unit hums but fan won’t spin
Burning smell or buzzing noise
Water leaking around indoor unit
Weak airflow from multiple vents
Breaker keeps tripping
Typical HVAC Repair Costs
Capacitor — $350–$550
Contactor — $350–$550
Refrigerant Leak Repair — $600–$1,500+
Blower / Airflow Issue — $600–$3,000
Condenser Fan Motor — $650–$2,000
Q: Is it bad to run AC if it isn’t cooling?
A: Yes — it can freeze the coil and/or damage the compressor.
Q: Why does my AC cool at night but not during the day?
A: Usually Airflow or low refrigerant — heat load exposes the issue.
Q: Can low refrigerant fix itself?
A: No. Refrigerant never gets used up. A leak exists.
Q: Why is upstairs hot but downstairs cool?
A: Airflow balance or attic heat gain — very common in Texas homes.