Air Conditioner is Off but It’s Still Blowing Air

Why Does Your Air Conditioner Keep Blowing Air When It’s Off?

If you find that your AC unit continues to blow air even when it’s turned off, you may have a problem, if left unaddressed, that results in unnecessary energy costs and poor comfort. Before you call a technician, here are some steps you can take to troubleshoot and possibly resolve the issue on your own.

Step 1. Check the Fan Setting

Problem: Often, the simplest explanation is the correct one. Your thermostat may be set to “Fan” or “On” instead of “Auto.” When it’s set to “Fan” or “On,” the fan will run continuously, even when the cooling or heating function is off.

Solution: Set your thermostat to “Auto” mode. In this setting, the fan will only run when the AC or heater is actively cooling or heating the air.

Step 2. Inspect the Thermostat

Problem: A malfunctioning or improperly wired thermostat can send incorrect signals to your HVAC system, causing it to act erratically.

Solution: Check the thermostat settings and make sure it’s properly wired. Consider replacing the thermostat if you suspect it’s faulty or if it’s an older model.

Step 3. Examine the Control Board

Problem: The control board inside your HVAC system could be malfunctioning, leading it to send continuous signals to the fan.

Solution: This is a job for a professional technician. They can diagnose the control board and replace it if necessary.

Step 4. Investigate Stuck Relays

Problem: A relay switch in your HVAC system may be stuck in the “on” position, causing the fan to run continuously.

Solution: A technician can identify and replace any faulty relays. This is not a DIY job.

Step 5. Check for Wiring Issues

Problem: Loose or damaged wires between the thermostat and the HVAC system can cause erratic behavior.

Solution: Inspect the wiring for any issues and ensure all connections are secure. Replace damaged wires as needed.

Step 6. Understand Cooling Delays

Problem: Some air conditioners have a cooling delay feature that keeps the fan running for a short time after the cooling cycle has stopped. This is normal.

Solution: No action is needed here; it’s part of the normal operation of your AC unit.

Step 7. Inspect Your Ductwork

Problem: Leaks or damaged ducts can lead to air continuing to flow even when the HVAC system is off.

Solution: Inspect your ductwork for visible issues and have any problems repaired by a professional.

Step 8. Consider External Factors

Problem: Sometimes, drafts from open windows, doors, or vents can mimic the feeling of the AC running when it’s not.

Solution: Ensure all windows and doors are closed and that vents are not open when the AC is off.

Step 9. Review HVAC System Settings

Problem: There may be specific settings or controls within your HVAC system that need adjustment.

Solution: Consult your system’s manual or contact the manufacturer for guidance on resetting or adjusting these settings.

Step 10. Check for a Power Interruption

Problem: Power interruptions or voltage spikes can disrupt the normal operation of your HVAC system.

Solution: Try power cycling the system by turning it off at the breaker for a few minutes and then turning it back on.

By following these steps, you can often identify and resolve the issue of your air conditioner blowing air when it’s supposed to be off. However, if you’ve tried these troubleshooting measures and the problem persists, contact a qualified HVAC technician. They have the expertise and tools to diagnose and address internal or electrical issues with your HVAC system.