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At What Temperature Should an Air Conditioner Be Set to Prevent Mold?

Meredith Jameson

A sometimes unexpected problem with air conditioners is the development of mold on the unit. This is due to the constant presence of interior moisture if the air conditioner is not run long enough. This may be avoided by setting the air conditioner at certain temperature points.


Fight mold by setting the temperature on your air conditioner.

A temperature setting of 78 degrees Fahrenheit when running the air conditioner is recommended for the best mold prevention. This temperature setting may also reduce cooling energy costs and reduce the relative humidity inside your home.

Temperature Setting

One of the primary reasons for an air conditioner developing mold is being set at a cold temperature point, causing it to reach that point quickly, then shut off. Once the unit shuts off, it cannot blow air through the system, removing moisture and reducing the likelihood of mold. If 78 degrees seems too warm for personal comfort, set the air conditioner at a temperature point approximately 10 degrees below the current air temperature.

Fan Mode

Set the fan mode on the air conditioner to "Auto" to allow the water that has pooled on the evaporator coil to drain off the coil and out of the unit. If the air conditioner fan switch is set to "On," it will run the blower fan constantly, causing the moisture to blow back into the home instead of draining down and out of the unit.

Humidity Setting

One of the best ways to prevent air conditioner mold is to use the humidity setting, if possible. The humidity setting on air conditioners will run the air handler fan at a lower speed, improving moisture removal. These units are generally also more energy efficient.