The Purpose of a CDTS
The primary purpose of the CDTS sensor is to reverse the action of the zone dampers when the system changes from cooling mode to heating mode and vis versa.
The CDTS is also used to hold the zone dampers in the closed position when the AC unit starts, until the supply air temperature is above the actual zone temperature.
The sensor can also be used (When the configuration option is activated) to improve efficiency of the system by using the hot and cold air in the ductwork to heat or cool the zones when the AC unit compressor has cycled off and the air temperature in the ductwork would assist in moving the zone closer to the set-point temperature.
The sensor can be used to monitor the approximate status of the compressor, however, the temperature readings should not be relied upon to determine if the compressor is working correctly as the supply air temperature will fluctuate, depending on the design of the system, staging of the inverter, the return air and the ambient temperature
A CDTS is only required on systems that have iZone temperature sensors for the control of the zones