One of the most popular combinations right now is the FV4 air handler with a 2 stage outdoor unit with a/c driven dehumidification. This combination is an awesome thing when it is adequately setup. When this system is installed and it is not setup or wired correctly it will not pull moisture from the home but instead cause the home to have higher humidity. I have made a guide to walk you through setup up and wiring this system to allow the homeowner to reap all of the benefits their system is capable of. This setup slows the blower down while running in the cool mode which causes the evaporator coil to be extremely cold. With the blower running slower and the coil being colder it allows more moisture to be removed from the air. If a home has high humidity due to infiltration, this setup will not correct their problem.

Sequence of operation for Dehum:

When dehum alone is needed (and overcool is setup) the unit will deenergize the ACC+ terminal and run the unit in cool. If overcool has been maxed out or has been set to zero then the thermostat will deenergize the ACC+ terminal but not run. The thermostat will wait for a cooling demand and deliver a reduced amount of airflow.