User Manual

Sequence of Operation
Fan Operation
17
Siemens Industry, Inc.
Application Note, App 14901
140-1230
2020-02-11
Figure 5: Compressor Staging with Ambient Lockout Activated.
Fan Operation
AUTO Mode – The fan relay is energized upon a call for heating or cooling per the
operating sequence. When there is no demand for heating or cooling (none of
heating/cooling stages are activated) the fan relay is de-energized.
The fan will turn ON when one of the following conditions has been met:
● In Heating mode, when the compressor or stage of electric heat is ON.
● In Cooling mode, 15 seconds before the first stage of cooling is energized.
The fan will turn OFF only after the following condition has been met:
● The compressor and stages of electric heat have been OFF for at least 30
seconds.
ON Mode – The fan relay is energized regardless of whether or not there is a call for
heating or cooling, unless the unit is set to Unit Off.
Fan Opr - Using Parameter P105 (HTG FAN), the fan relay can be set to be energized
or not energized upon call for heat. This parameter does not apply to compressors; the
fan relay should be energized upon a call for heat on Y1/Y2 regardless of the setting of
the parameter.