On the display
The panel prints FLOW SWITCH OPEN. The manual lists the message under the unit safeties, and the Native BACnet, Modbus, and N2 communications data map carries the same code under the name Flow Switch Open, reported via the Sys 1 / Sys 2 Fault Code points. In the YLAA Fault and Inhibit Codes it is listed as Unit Fault Code 31 (auto reset).
What it means
The message indicates that the flow switch contacts connected to Terminals 13 and 14 of XTBC1 are open. A 3-second delay is built into the software to prevent nuisance shutdowns due to erroneous signals from the flow switch, so a brief erroneous signal on this input does not shut the unit down.
Why it appears
- The flow switch contacts connected to Terminals 13 and 14 of XTBC1 are open. This is the only cause the manual gives for the message.
Setpoints and thresholds
- 3-second delay built into the software on the flow switch input, to prevent nuisance shutdowns due to erroneous signals from the flow switch.
Reset and restart
This fault resets automatically. The manual lists Unit Fault Code 31 as an auto-reset fault, and its auto-reset table (Table 15) allows restart once meeting the required conditions
. No manual reset procedure is described for this message — the unit restarts on its own once the required conditions are met.
Questions engineers ask
What does FLOW SWITCH OPEN mean on a YORK YLAA?
It means the flow switch contacts connected to Terminals 13 and 14 of XTBC1 are open. The control lists it as Unit Fault Code 31 under the unit safeties.
How do I reset FLOW SWITCH OPEN on a YLAA chiller?
It resets itself — the manual lists Unit Fault Code 31 as an auto-reset fault, and the auto-reset table allows restart once the required conditions are met. No manual reset step is described.
Why does the YLAA wait before tripping FLOW SWITCH OPEN?
A 3-second delay is built into the software to prevent nuisance shutdowns due to erroneous signals from the flow switch.
Where does the flow switch wire into a YORK YLAA?
The flow switch contacts are connected to Terminals 13 and 14 of XTBC1, per the manual's description of this fault.
Messages next to this one
Source
Written from the manufacturer's manuals for the YORK YLAA; every number and designation on this page is checked against them before publication. The row of the manual this message comes from:
All YORK YLAA messages: fault codes · YORK YLAA documentation · YORK manuals