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Can you change AC filter with AC on?

Published in AC Filter Replacement 3 mins read

No, you should never change an air conditioner filter while the unit is running. It is crucial to turn off the AC system completely before attempting to replace the filter.

Changing your AC filter is a simple maintenance task, but performing it while the unit is operational can pose significant risks and issues. The primary recommendation from experts and guides is to ensure the power is off first.

Why You Should Turn Off Your AC Before Changing the Filter

According to maintenance guidelines, powering down your air conditioner is essential for two main reasons when it's time to change the filter:

  1. Safety Concerns: Working on any appliance with the power on creates a safety hazard. Live electrical components are present in or near your HVAC system. Turning off the power, typically at the thermostat and possibly the breaker panel, eliminates the risk of electrical shock while you are working on the filter housing.
  2. Preventing System Damage: An AC filter is designed to capture dust, dirt, and debris before they enter the system's air handler and coils. When you remove the old filter while the fan is running, there is a brief period where the air intake is unfiltered. During this time, the system can suck in dust and debris from the surrounding environment directly into the sensitive internal components. This can lead to:
    • Clogged coils, reducing efficiency and potentially causing freezing.
    • Dirt build-up on the blower motor.
    • Reduced system performance and potential need for costly repairs.

Step-by-Step: How to Safely Change Your AC Filter

To ensure both your safety and the longevity of your HVAC system, always follow these steps when changing your filter:

  • Locate the Filter: Filters are typically found in the air return vent grill or near the air handler unit itself.
  • Turn Off the System: Go to your thermostat and switch the system mode from "Cool" or "Heat" to "Off". It's also a good practice to turn off the fan by switching it from "On" to "Auto" or "Off". For added safety, consider switching off the dedicated breaker for the HVAC system.
  • Remove the Old Filter: Open the filter housing or grill. Note the direction of the airflow arrow on the filter (it should point towards the air handler unit). Carefully slide out the old, dirty filter.
  • Insert the New Filter: Ensure the new filter is the correct size. Position the new filter so the airflow arrow points in the same direction as the old one (towards the air handler). Slide it into the housing or grill.
  • Secure the Housing: Close and secure the filter housing or grill.
  • Restore Power: Turn the HVAC system's breaker back on if you switched it off.
  • Restart the System: Go back to the thermostat and set the system mode and fan settings back to your desired configuration (e.g., "Cool" and "Auto").

By taking a few moments to properly power down your system, you protect yourself from electrical hazards and prevent dirt from bypassing the filter and damaging your HVAC unit.