AUX Contacts on Communicating Furnace PCBsby HVAC Distributors December 21, 2023
Daikin has released Technical Service Bulletin TSB D-PC-0040 related to AUX Contacts on Communicating Furnace PCBs.
We are providing notification to service technicians regarding the AUX contacts on communicating furnace control boards when the system is wired with a communicating thermostat. Currently, the AUX contacts will not shut off the communicating outdoor unit in the event of a condensate float switch opening. An Over-the-Air (OTA) update for the communicating furnace control boards, which will enable the use of the AUX contacts for the float switch operation, has already been released for the CoolCloud HVAC app and is scheduled to be included into production for communicating furnace control boards in early 2024.
Information in this bulletin does not apply if a standard 24VAC thermostat is used along with a noncommunicating outdoor unit or a communicating outdoor unit in a ComfortBridge setup. In a standard ComfortBridge setup, the AUX contacts can be used with a float switch. Pushing the OTA is not going to negatively impact performance for a system using a 24VAC thermostat. If a communicating furnace is connected to a standard 24VAC thermostat as a fully non-communicating system (outdoor unit is noncommunicating), the Y connection to the outdoor unit should be wired through the float switch connections.
If you have technical questions, please contact our Technical Support team.