Amana window or PTAC AC displays CF periodically; unit may beep but continues to run.

Safety first: Turn the unit off before removing the front grille.

Steps to address CF (clean filter):

• Remove and clean filter: Take off the front panel, slide out the air filter, and wash it with warm water and mild detergent. Rinse thoroughly and let it dry completely before reinstalling.
• Reset filter timer: Press and hold the designated filter reset button (often "Filter" or a combination like "Fan" + "Temp Down") for 3–5 seconds until CF clears. Refer to the user manual for your specific model.
• Inspect coil: While the filter is out, visually check the evaporator coil for dust buildup. If dirty, gently vacuum with a soft brush.

Running the unit with a clogged filter reduces efficiency and can cause icing or error codes related to low temperature.