I have the following system that has been installed for about 3 weeks:
- Trane 4TTX6060E1000B (XL16i) condenser
- Trane TUD2D120B9V5VB (XV80) furnace
- Trane 4TXCD063BC3H evaporate coil
- Trane TCONT802AS32DA (802) thermostat - recently changed to a Nest 2nd generation

I know that a common problem with the XL16i is incorrect wiring. As such, I reviewed it in-depth and made sure that the wiring, switches (settings), etc. all match what the installer guides call for to match the equipment. The first and second stages are wired correctly to the XL16i using the BK terminal in the furnace.

We do have Comfort-R enabled via the dip switches, air flow at 400 CFM/ton, 5 ton, etc.

The one setting that is different than what the manuals seem to call for is dip switch S5-2. The switch is currently set to ON (which translates to De-Humidifier is Not Installed) on my furnace. We do not have a de-humidifier so this makes sense at first glance. However, the XL16i manual says switch S5-2 should be OFF. Additionally, there is Note 9 of the furnace installer guide that references that S5-2 must be OFF when the BK terminal is being used for an airflow command signal.

My questions are:
1) Should switch S5-2 be ON or OFF for this setup?
2) When they are saying OFF, are they referring to the physical position of the switch (OFF as printed on the circuit board) or OFF as in de-humidifier is not installed (which really is ON on the switch)?
3) Can anyone explain what the difference is the different settings of this switch (e.g. if has supposed to have been OFF all this time, then what has having it ON been doing)?

Thanks.