Carrier ducted-split — Carrier Infinity System Control paired with communicating equipment, with the outdoor-unit code structure documented for 24VNA6 and 25VNA4 variable-speed units Error Codes Directory

Carrier Infinity code 16 with 53, 55 or 47: telling a communication fault from a failed sensor

Read the number as a pair before deciding anything. On 24VNA6 and 25VNA4 equipment the outdoor board reports a base code plus an expansion code, so 16, 53 and 55 occupy different columns of one table and carry different meanings depending on the column they came from. A genuine loss of communication with the Infinity System Control sets no diagnostic fault at the outdoor unit: the service manual says the Comm light goes off and the equipment falls back to its discrete control inputs. Applies to: Carrier Infinity System Control paired with communicating equipment, with the outdoor-unit code structure documented for 24VNA6 and 25VNA4 variable-speed units The code structure described here is the one published for the 24VNA6 and 25VNA4 outdoor units. Carrier furnaces, fan coils and older Infinity outdoor sections keep their own tables, and a two-digit number copied from one of those is not evidence about a variable-speed unit carrying this board. Owner-safe checks: Photograph the wall control message, the outdoor display, and the state of the Comm light before any power is interrupted. | Write down whether the number appeared in a code position or in a temperature field on a status screen. | Note which modes the system still accepts, because a mode that runs is evidence about what the control is protecting. Qualified technician: Resistance measurement at the control board connector, and any inspection inside the outdoor cabinet, is qualified service work. | Tracing the communication path between the outdoor board and the Infinity System Control involves energised low-voltage wiring and belongs to a technician.