Contrary to popular belief, fan speed settings aren’t always correct from the factory. It’s been a long-standing assumption that you should use the high-speed tap for cooling and low-speed tap for heating when using a constant-speed fan. The same type of assumption leads users to believe their variable-speed dip switches are correctly preset from the factory.
This type of guesswork often leads to customer complaints, poor system performance, and frustrating callbacks that can be avoided with a little bit of upfront planning, preparation, and testing. Let’s look at how to set fan airflow based on the needs of the equipment in both cooling and heating mode.