Your air handler unit controls the hot and cold air that blows into your home's forced air system. Heating and cooling coils on air handler units can get covered in dirt, dust, algae and mildew over time, causing them to work less effectively. Cleaning the coils with a mixture of water and muriatic acid will clean all of the build-up off and keep the coils in working condition. The coils should be cleaned at least once a year.
Turn off the air handler and open the unit's door with a wrench, if needed.
Remove the coils from the unit and take them outside. The coils should be removed with the wrench.
Add 10 parts water to a bucket and pour one part muriatic acid into the water. Wear the gloves and goggles when working with the acid. Dip the coils into the acid mixture for up to five minutes.
Rinse the coils well with the hose to remove all the build-up.
Place the coils back into the air handler unit and turn it back on.