When your AC runs but the house stays warm, something is preventing the system from cooling effectively. Here are the most common causes and what you can do about each.
1. Dirty Air Filter
A severely clogged filter restricts airflow to the point where the system cannot cool effectively. The evaporator coil may even freeze due to reduced airflow.
Solution: Check and replace the filter. If ice has formed, turn off the AC and let it thaw before running again.
2. Thermostat Issues
The thermostat might be set incorrectly, have dead batteries, or be malfunctioning.
Solution: Verify the thermostat is set to COOL with a temperature below room temperature. Replace batteries. If issues persist, the thermostat may need replacement.
3. Dirty Condenser Coils
The outdoor condenser releases heat from your home. When coils are dirty, heat rejection is reduced and cooling suffers.
Solution: Clean the condenser coils following safe procedures. Ensure nothing is blocking airflow around the unit.
4. Refrigerant Leak
Refrigerant is the substance that carries heat from inside to outside. If it leaks, cooling capacity drops. AC systems do not consume refrigerant; if levels are low, there is a leak.
Solution: This requires professional repair. A technician will find and repair the leak, then recharge the system.
5. Frozen Evaporator Coil
Ice on the indoor coil prevents cooling. Causes include dirty filters, low refrigerant, or blower problems.
Solution: Turn off the AC and let ice melt completely. Check the filter. If freezing recurs, call for service.
6. Compressor Problems
The compressor is the heart of the system. If it fails or runs poorly, cooling stops.
Solution: Compressor issues require professional diagnosis and repair. This is often a significant repair or replacement decision.
7. Ductwork Problems
Leaky or disconnected ducts can lose most of your cooled air before it reaches living spaces.
Solution: Inspect accessible ductwork for disconnections or obvious damage. Professional duct testing reveals hidden leaks.
When to Call for Help
If checking the filter and thermostat does not resolve the issue, professional diagnosis is needed. Refrigerant, electrical, and compressor issues require trained technicians with proper equipment.
Continuing to run a malfunctioning system can cause additional damage. If your AC is not cooling effectively, getting it checked promptly often saves money in the long run.